Check List

Brief Summary Of Operation

POWER TRAIN SYSTEMS BASIC DIAGRAM (SIMPLIFIED)

1. The transmission speed sender measures (senses) ground speed.

2. The transmission control determines when to shift from the signal of the ground speed. The transmission control activates the solenoids to make shifts.

3. The bed raise switch or the transmission (XMSN) test switch is used in the test mode (condition). The bed raise switch also prevents REVERSE operation of the transmission during RAISE operation of the body.

4. The secondary brake switch, service brake switch, and retarder switch provide an input to the transmission control. The secondary brake or service brake switch will deactivate the anti-hunt. The retarder switch when activated will make the shift speeds higher.

5. The transmission speed distributor lets the same output from the transmission speed sender to be used for the speedometer.

6. When an upshift or downshift solenoid is activated, it sends pressure oil to the rotary actuator which turns the rotary selector spool. This sequence causes a different pair (two) of clutches to be engaged for the next speed.

7. Transmission hydraulic controls individually (separately) control the time to engage (fill time) and disengage (release time) each clutch and the maximum pressure in each clutch.

8. The lockup solenoid is activated to send pressure oil to the modulation reduction valve to engage the lockup clutch of the torque converter for direct drive.

Information On Check Lists

The power train (electrical, hydraulic, torque converter, transmission, etc.) can be checked for correct operation with the assistance of a check list. The check list is a shorter form of the operational checks, electrical tests, hydraulic tests, transmission tests and torque converter tests. A check list is designed to give assistance to the WELL TRAINED service personnel. The service personnel can make their own check list if the check list supplied does not match the needed use. The check list must NOT be used unless the OPERATIONAL CHECKS, TRANSMISSION TESTS, TORQUE CONVERTER TESTS, HYDRAULIC TESTS, and ELECTRICAL TESTS for this machine have been read and understood completely.

A check list is designed with a sequence to find the most probable cause of a problem quickly. The check list that follows must be done in order. DO NOT go to the next check if a problem has been noted. The "Preparation of Machine For Operational Checks" must be completed before starting any check list.

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Check lists DO NOT include WARNINGS or NOTICES to indicate a procedure where personal injury or damage to the machine can happen. If ALL warnings and notices found in the OPERATIONAL CHECKS, TRANSMISSION TESTS, TORQUE CONVERTER TESTS, HYDRAULIC TESTS, and ELECTRICAL TESTS are NOT known or understood, DO NOT use a check list form.

Specifications For 768C & 769C Torque Converters And Transmissions

Torque Converters

Transmissions

Power Train Systems

General Description

The power train is made up of four basic systems.

1. Transmission Control (Electrical System).

2. Torque Converter.

3. Transfer Gears and Transmission.

4. Differential and Final Drives.

These four basic systems connect to each other either electrically, hydraulically or mechanically. A basic diagram shows what components are common to each system.

POWER TRAIN SYSTEMS BASIC DIAGRAM (SIMPLIFIED)

COMPONENTS OF THE POWER TRAIN
1. Differential and bevel gear. 2. Pinion. 3. Transmission. 4. Transfer gears. 5. Front drive shaft. 6. Torque converter. 7. Final drives and axles. 8. Wheels and tires. 9. Rear drive shaft. 10. Lockup clutch. 11. Engine.

REAR OF CAB
12. Transmission control.

Transmission control (12) matches the transmission speed to the selected speed of transmission shift lever (13). The transmission control gets information of the selected speed of operation through the electrical system. The transmission control electrical system activates the hydraulic systems (transmission and torque converter) through solenoids (upshift, downshift and lockup solenoids).

RIGHT SIDE OF OPERATOR'S SEAT
13. Transmission shift lever. 14. Shift lever switch (inside console).

Torque converter (6) has a lockup clutch (10) for direct drive and a one-way clutch for torque converter drive. The torque converter is fastened directly to the flywheel of engine (11).

FRONT OF TRANSFER GEARS
15. Transmission speed sender.

The torque converter drives transmission (3) hydraulically, unless the lockup clutch is activated. When the lockup solenoid is activated, the lockup clutch is hydraulically engaged. The rotating (input) housing of the torque converter is now mechanically connected to the output shaft of the torque converter. Front drive shaft (5) mechanically connects the torque converter to transfer gears (4). The transfer gears are fastened directly to the transmission.

RIGHT SIDE OF TRANSMISSION
16. Downshift solenoid. 17. Upshift solenoid. 18. Plug for access to the rotary selector spool.

Upshift solenoid (17) and downshift solenoid (16) hydraulically activate the transmission hydraulic control group. The transmission hydraulic control group activates the transmission clutches which cause the mechanical connection to the transmission output shaft. The transmission clutches will not drive the transmission output shaft unless the torque converter is activated (either hydraulically or mechanically).

INNER RIGHT SIDE OF MAIN FRAME
19. Inlet relief valve. 20. Transmission oil filter. 21. Torque converter oil filter. 22. Outlet relief valve. 23. Lockup clutch and solenoid valve group. 24. Secondary and parking brake control valve. 25. Oil pump for torque converter and brakes.

LEFT SIDE OF MAIN FRAME
26. Return oil screen. 27. Return oil filter. 28. Hydraulic oil tank. 29. Transmission oil tank.

The transmission has seven forward speeds and one reverse speed. The selection of speed is done manually, in REVERSE, NEUTRAL and FIRST. The selection of SECOND through SEVENTH speeds is done either manually or automatically.

REVERSE is torque converter drive only. FIRST has both a torque converter drive and a direct drive. SECOND through SEVENTH speeds are direct drive only with a very short time of converter drive during transmission clutch engagement to make shifts smooth. Rear drive shaft (9) connects the transmission to differential and bevel gear (1). The differential and bevel gear are fastened directly to the rear axle housing.

After the transmission and torque converter are connected, power can now be supplied from the engine (through the transmission and torque converter) to the differential. The rear axles mechanically connect the differential to the final drives. The final drives are connected to the rear wheels. Power is now sent to the tires.

REAR OF TORQUE CONVERTER
30. Hydraulic oil breather. 31. Transmission oil breather.

When the transmission is in the correct speed position, the mechanical movement of the rotary selector spool causes the transmission switch to electrically signal the transmission control that the shift is complete. With the rotation of the output shaft of the transmission, transmission speed sender (15) electrically signals the transmission control that the machine has moved.

RIGHT SIDE OF ENGINE
32. Oil cooler for torque converter and brakes.

The torque converter has a hydraulic system that uses oil that is also common with the brake cooling system, the parking brake release system and the hoist or wagon (trailing unit) hydraulic system. These systems all use the same SAE 10W oil from hydraulic oil tank (28). Lockup clutch and solenoid valve group (23), inlet relief valve (19), outlet relief valve (22), oil pump (25), charging oil filter (21) and lockup clutch (10) are some of the components in this system.

FRONT OF ENGINE
33. Transmission oil cooler.

Pressure oil to engage the lockup clutch comes from the parking brake release system. The oil goes through oil filter (36) to secondary and parking brake valve (24) before it goes to lockup clutch and solenoid valve group (23). This valve group controls the operation of lockup clutch (10).

REAR OF OIL PUMP DRIVE AND TORQUE CONVERTER
25. Oil pump for torque converter and brakes. 34. Oil pump for transmission. 35. Magnetic screen.

Oil from outlet relief valve (22) is used to cool the wheel brakes. Oil that is not needed by the hoist or wagon hydraulic system also is used to cool the wheel brakes. These two oils go through oil cooler (32) before they go to the brakes. The oil then goes back through return oil screen (26) and into hydraulic oil tank (28).

OUTER RIGHT SIDE OF MAIN FRAME
36. Parking brake release oil filter.

The transmission has its own hydraulic system. It uses SAE 30W oil from transmission oil tank (29). Other components in this system are: a transmission hydraulic control group, oil pump (34) with two sections, oil filter (20), magnetic screen (35), return oil filter (27) and transmission oil cooler (33).

The basic components of the transmission hydraulic control group are downshift solenoid (16), upshift solenoid (17), pressure control group (37), selector group (38) and rotary actuator (39). The solenoids are the connection between the electrical and hydraulic systems. The solenoids are activated electrically and send oil to rotary actuator (39). The rotary actuator turns rotary selector spool (40) in selector group (38) which sends pilot oil to pressure control group (37). Pressure control group (37) then sends oil at the correct rate to smoothly engage the correct clutches in the transmission.

LEFT SIDE OF TRANSMISSION HYDRAULIC CONTROL GROUP
16. Downshift solenoid. 17. Upshift solenoid. 37. Pressure control group. 38. Selector group. 39. Rotary actuator. 40. Rotary selector spool.

When plug (18) is removed, rotary selector spool (40) can be manually moved through all of its positions when the engine is off. When rotary selector spool (40) is turned clockwise as far as it will go, the spool [and rotary actuator (39)] is in NEUTRAL position. From NEUTRAL each detent position in the counterclockwise direction is REVERSE, FIRST, SECOND, THIRD, FOURTH, FIFTH, SIXTH, SEVENTH AND EIGHTH speeds respectively (EIGHTH speed position is not used on 700 series machines).

Procedure To Turn The Rotary Selector Spool

Rotary selector spool (40) can be manually moved through all of its positions when the engine is off.

1. Remove plug (18) from the transmission case.

2. Install a 9S1743 Extension [.25 (1/4) in. sq. drive] 4 in. long in the end of rotary selector spool (40). Install a 9S1712 Reversible Ratchet on the extension.

3. Move the ratchet toward the rear of the machine until the rotary selector spool will not turn any more (turn the rotary selector spool clockwise as far as it will go). This is NEUTRAL position.

4. From NEUTRAL position, turn the ratchet counterclockwise (toward the front of the machine) through all detent positions of the rotary selector spool. The positions from NEUTRAL are REVERSE, FIRST, SECOND, THIRD, FOURTH, FIFTH, SIXTH, SEVENTH and EIGHTH speeds respectively (EIGHTH speed position is not used on 700 series machines).

NOTE: There is approximately 30° of rotation between each detent of rotary selector spool (40).

RATCHET AND EXTENSION INSTALLED IN THE ROTARY SELECTOR SPOOL

Shift Inhibiting

A shift from any speed into NEUTRAL is not inhibited (prevented). The transmission can always be shifted to NEUTRAL.

If the ground speed of the machine is less than 5 km/h (3 mph) in any forward speed and the transmission shift lever is moved to REVERSE, the transmission will immediately shift to REVERSE. If the ground speed is more than 5 km/h (3 mph) in any forward speed and the transmission shift lever is moved to REVERSE, the transmission will not immediately make a shift to NEUTRAL. The transmission will then shift to REVERSE, when the ground speed gets less than 5 km/h (3 mph).

Troubleshooting The Power Train

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Sudden movement of the machine can cause injury to persons on or near the machine. To prevent possible injury, do the procedure that follows before troubleshooting the power train.

1. Move the machine to a smooth horizontal location. Move away from working machines and personnel. Put the transmission shift lever in NEUTRAL position. Stop the engine.

2. Permit only two people in the cab (one operator and a service person). The machine operator must only operate the machine as told by the service person. The service person will look at all lights (LED'S) or gauges. Keep all other personnel either away from the machine or in view of the operator.

3. Activate the parking brakes.

4. Make sure the transmission rotary selector spool is in NEUTRAL position.

For locations of components and electrical connectors, see the POWER TRAIN ELECTRICAL SCHEMATIC. For hydraulic components or pressure tap locations see the TORQUE CONVERTER AND TRANSMISSION HYDRAULIC SCHEMATICS.

Operational Checks

The operational checks that follow are designed to educate (train) the service personnel in a correct troubleshooting procedure and method. The checks and procedures are set in a sequence to find most problem(s) and/or probable cause(s) quickly. These operational checks must be done in order, starting with CHECK 1. Do not go to the next check until either the problem in the previous (before) check has been corrected, or instructed to do so. If the correct result for the check is found, as instructed in the procedure, go directly to the next check (or procedure for the trained service personnel).

Take note of all WARNINGS and NOTICES in these checks. Never start the next check until the warnings or notices are read and understood completely.

The checks that follow can be used to find many of the problems that will be found during the operation of the machine. These checks will also give an indication of the system in which the problems can be found.

Preparation of Machine For Operational Checks

1. Put the parking brakes ON. When the transmission shift lever and the transmission rotary selector spool are in the NEUTRAL position, the lights (LED's) on the transmission control must be as shown.

Be sure the shift lever and the transmission rotary selector spool are in NEUTRAL position.

2. Check all fluid levels on the machine (engine oil, engine coolant, hydraulic oil, differential, transmission, etc.). Make sure the torque converter oil is SAE 10W oil, transmission oil is SAE 30W oil and that No. 2 diesel fuel is used for the engine fuel.

NOTE: The oil levels can be above the FULL mark at this time. With the engine running, both transmission and torque converter oil must be at the normal temperature for operation.

3. Check engine performance by doing a full stall in the REVERSE speed position.

4. The engine must be OFF. Keep the engine OFF until told differently.

5. The tachometer must be at zero rpm.

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Some of the checks that follow must be done with the machine in operation. A trained machine operator will be needed. To prevent possible injury, do the procedure that follows. 1. Move the machine to an area that is smooth and level and free of other machines. 2. Put the front brakes on-off valve, on the instrument panel, in the ON position. 3. Whenever the engine is in operation, the machine operator must be in the cab with the parking and service brakes ON until told differently.

Check 1:

This check will show if:

a. The torque converter is locked up (output yoke will not turn).

b. The transmission and transfer gears are locked up (input yoke will not turn).

PROCEDURE:

1. Turn the drive shaft by hand. If the drive shaft turns freely, go to CHECK 2.

2. If the drive shaft does not turn, disconnect the drive shaft from the output yoke of the torque converter.

3. Separately turn the output yoke of the torque converter and the input yoke of the transfer gears.

PROBLEM 1:

The output yoke of the torque converter does not turn.

PROBABLE CAUSE:

a. See TROUBLESHOOTING THE TORQUE CONVERTER HYDRAULIC SYSTEM, do Visual Checks.

PROBLEM 2:

The input yoke of the transfer gears does not turn.

PROBABLE CAUSE:

a. See TROUBLESHOOTING THE TRANSMISSION HYDRAULIC SYSTEM, do Visual Checks.

Check 2:

This check will show if:

a. The transmission control has power.

b. All of the indicator lights (LED's) work.

c. The bed raise switch (adjustment and circuit) works correctly on the truck. The XMSN (transmission) test switch works correctly on the tractor.

PROCEDURE:

1. Turn the disconnect and key start switches to their ON positions. DO NOT START THE ENGINE.

2. Put the hoist lever in the RAISE position on the truck. Activate the spring loaded XMSN test switch on the tractor. The transmission control lights (LED's) must be as shown.

PROBLEM 1:

Lights L1 thru L5 and G1 thru G5 are CORRECT all of the other lights are NOT ON.

PROBABLE CAUSE:

a. Bad transmission control.

PROBLEM 2:

All of the lights are OFF on the transmission control.

PROBLEM 3:

Some, but not all, lights L1 thru L5 and G1 thru G5 are ON.

PROBABLE CAUSE:

a. Electrical system. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

Check 3:

This check will show if:

a. The hoist lever and bed raise switch release and the circuit operates correctly on the truck. The XMSN test switch releases on the tractor.

b. The shift lever switch is in the correct position.

c. The transmission switch is in the correct position.

PROCEDURE:

Put the hoist lever in the FLOAT position on the truck. Deactivate (make not active) the spring loaded XMSN test switch on the tractor. The transmission control lights (LED's) must be as shown:

PROBLEM 1:

All lights are ON.

PROBABLE CAUSE:

a. Hoist lever and/or bed raise switch are not adjusted correctly on the truck. XMSN test circuit and/or switch is bad (open) on the tractor.

b. Electrical system. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

PROBLEM 2:

The lights are not as shown above.

PROBABLE CAUSE:

a. Broken (open) ground verify (716-BU or 726-BU) wire from the transmission control to the switches.

b. Electrical system. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

Check 4:

This check will show if:

a. The shift lever switch operates and is installed (timed) correctly.

b. The transmission control operates.

PROCEDURE:

1. Put the transmission shift lever in the REVERSE position and all FORWARD speeds (FIRST through SEVENTH). The upshift solenoid will activate and the transmission control lights (LED's) must be as shown.

2. When this check is complete put the shift lever in the NEUTRAL position.

PROBLEM 1:

The lights are not as shown above.

PROBABLE CAUSE:

a. Electrical system. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

Check 5:

Some of the OPERATIONAL CHECKS must use the machine tachometer. If the machine tachometer does not operate correctly, replace the tachometer, or use the 6V3121 MULTITACH GROUP.

6V3121 MULTITACH GROUP

The 6V3121 Multitach Group can measure engine rpm by the use of either the photo pickup and reflective tape, or a magnetic pickup or tachometer generator. Special Instruction Form No. SEHS7807 has instructions for its use.

PROCEDURE:

Start and run the engine at LOW IDLE rpm. Check to see that the tachometer operates correctly. As the governor pedal is pushed down, an increase in engine rpm must be seen on the tachometer.

PROBLEM 1:

Tachometer does not show engine rpm.

PROBABLE CAUSE:

a. Bad tachometer or tachometer drive unit.

Check 6:

This check will show if:

a. The hoist hydraulic system (on a truck) operates correctly.

b. The wagon (trailing unit) hydraulic system operates.

PROCEDURE FOR TRACTORS:

1. Make sure that the brake (wagon hydraulics and torque converter) oil is at normal operating temperature.

2. With the tractor engine at LOW IDLE rpm, operate the wagon hydraulic system. Make sure that the hydraulic cylinders fully extend and retract.

3. Do Step 2 again with the tractor engine at HIGH IDLE rpm.

4. Stop the engine.

PROCEDURE FOR TRUCKS:

1. Make sure that the brake (hoist and torque converter) oil is at normal operating temperature.

2. Make sure the body is down against the main frame.

3. With the truck engine at HIGH IDLE rpm, measure the time it takes for the body to lift from the main frame to its maximum height.

4. The time for the hoist cylinders to fully extend (lift the body to maximum height) must not be over the time found in the hydraulic systems specification. For example: on the 777 Truck the approximate time is 16 seconds. On the 769C and 773B Trucks, the approximate time is 11 seconds.

5. Install the body retaining pins to keep the body in the RAISE position.

6. Stop the engine.

7. Disconnect the hoist control linkage.

PROBLEM 1:

Truck body does not lift.

PROBABLE CAUSE:

a. See Hydraulic (Hoist and Wagon) System Testing and Adjusting.

PROBLEM 2:

Truck body lifts too slowly.

PROBABLE CAUSE:

a. See Hydraulic (Hoist and Wagon) System Testing and Adjusting.

PROBLEM 3:

Wagon (trailing unit) cylinders do not move.

PROBABLE CAUSE:

a. See Hydraulic (Hoist and Wagon) System Testing and Adjusting.

PROBLEM 4:

Wagon cylinder movement is not smooth at both low and high idle rpm.

PROBABLE CAUSE:

a. See Hydraulic (Hoist and Wagon) System Testing and Adjusting.

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On a truck, the body (bed) must be fully in the RAISE position for the Operational Checks that follow. Make sure the body retaining pins are correctly installed. To prevent possible injury of the service personnel and damage to the body retaining pins, disconnect the hoist control linkage. (Remove cotter pin and pin as shown.).

HOIST CONTROL LINKAGE DISCONNECTED

PINS INSTALLED IN BODY OF TRUCK

Check 7:

This check will show if the rotary actuator and rotary selector spool have the ability to move when the electrical and hydraulic systems operate correctly (the rotary actuator and rotary selector spool are not locked up).

PROCEDURE:

1. With the engine OFF, remove the plug for the rotary selector spool from the left side of the transmission case.

2. Put a .25 (1/4) in. sq. drive extension 4 in. long in the end of the rotary selector spool. Put a ratchet on the extension.

METHOD TO TURN THE TRANSMISSION ROTARY SELECTOR SPOOL

3. Move the ratchet (rotary selector spool) counterclockwise through all speed positions (as far as it will go). The order of the detent positions is: N, R, 1, 2, 3, 4, 5, 6, 7 and 8 (8th is not used on 700 series machines). The detents must be felt for each speed position of the spool.

PROBLEM 1:

Rotary selector spool will not move (rotate).

PROBABLE CAUSE:

a. Bent or broken detent springs on the transmission rotary selector spool.

b. Foreign material will not permit movement of rotary actuator. Disassemble the rotary actuator of the transmission hydraulic controls. Check for foreign material, worn or damaged parts.

c. Foreign material or a defect will not permit movement of rotary selector spool. Disassemble the selector group of the transmission hydraulic controls. Check for foreign material, worn or damaged parts.

Check 8:

This check will show if:

a. The transmission switch operates and is installed (timed) correctly.

b. The transmission control operates.

PROCEDURE:

1. The transmission shift lever must be in NEUTRAL position, and the plug removed (on the left side of the transmission case) from the transmission (for manual shifting of the rotary selector spool).

2. With the disconnect and key start switches in their ON positions, DO NOT start the engine.

3. Put a .25 (1/4) in. sq. drive extension 4 in. long in the end of the rotary selector spool. Put a ratchet on the extension.

4. Turn the rotary selector spool from NEUTRAL to each speed position through EIGHTH speed. EIGHTH speed position is not used in the 700 series machine, but check it also.

5. The transmission control lights (LED's) must be as shown.

6. Put the transmission rotary selector spool back in NEUTRAL position (clockwise as far as it will go) when this check is complete.

PROBLEM 1:

The lights are not as shown above.

PROBABLE CAUSE:

a. Electrical system. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

Check 9:

This check will show if:

a. The electrical signal gets to the downshift solenoid.

b. The downshift solenoid will electrically activate.

PROCEDURE:

1. With the transmission shift lever and the transmission rotary selector spool in NEUTRAL, the harness connector for the downshift solenoid must be disconnected. The downshift solenoid light (LED) must be ON as shown.

2. Touch (put) the harness connector to the downshift solenoid. Each time the connector is touched to the downshift solenoid a "click" or "buzz" will be felt and/or heard.

3. When this check is complete, DO NOT connect the harness connector to the downshift solenoid.

PROBLEM 1:

Downshift solenoid light (LED) is OFF on the transmission control.

PROBABLE CAUSE:

a. The transmission control is bad.

PROBLEM 2:

The "click" and/or "buzz" is not felt or heard.

PROBABLE CAUSE:

a. Bad downshift solenoid.

b. Broken (open) wire or harness to the downshift solenoid. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

Check 10:

This check will show if:

a. The electrical signal gets to the upshift solenoid.

b. The upshift solenoid will electrically activate.

c. The ground verify wires are connected to vehicle ground.

PROCEDURE:

1. Move the transmission shift lever to the REVERSE speed position. The upshift solenoid light (LED) must be ON as shown.

2. Remove the harness connector from the upshift solenoid.

3. Touch the harness connector to the upshift solenoid. Each time the connector is touched to the upshift solenoid a "click" or "buzz" will be felt and/or heard.

4. When this check is complete, DO NOT connect the harness connector to the upshift solenoid. Put the shift lever back in the NEUTRAL position.

PROBLEM 1:

Upshift solenoid light is OFF on the transmission control.

PROBABLE CAUSE:

a. The transmission control is bad.

PROBLEM 2:

The "click" and/or "buzz" is not felt or heard.

PROBABLE CAUSE:

a. Bad upshift solenoid.

b. Broken (open) ground verify (716-BU or 726-BU) wire from the transmission control to the switches. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

c. Broken (open) wire or harness to the upshift solenoid. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

Check 11:

This check will show if the lockup solenoid will activate electrically with the use of the machine harness and components (not including the transmission control).

PROCEDURE:

1. Disconnect the cab harness plug from the transmission control. Put a jumper wire from Socket 1 to Socket 5 of the cab harness plug (for the transmission control). This supplies +24 volts through the machine harness to activate the lockup solenoid.

LOCKUP SOLENOID CONNECTOR

JUMPER WIRE AT THE TRANSMISSION CONTROL HARNESS CONNECTION (FROM SOCKET 1 TO SOCKET 5)

2. Touch the lockup solenoid chassis harness connector to the lockup solenoid.

3. Each time the connector touches the solenoid a "buzz" and/or click must be felt or heard.

4. When this check is complete, DO NOT connect the harness connector to the lockup solenoid or the transmission control.

PROBLEM 1:

The "click" and/or buzz cannot be either felt or heard when the harness connector is touched to the solenoid.

PROBABLE CAUSE:

a. Bad lockup solenoid.

b. Broken (open or grounded) wire or harness to the lockup solenoid. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

Check 12:

This check will show if:

a. The service brakes (all four) are good.

b. The transmission and torque converter pressures are approximately correct.

c. The transmission clutches engage correctly.

d. The torque converter (without the lockup clutch engaged) operates correctly.

PROCEDURE:

1. With all electrical harness connectors still removed from the upshift, downshift and lockup solenoids, start the engine and run at LOW IDLE rpm.

2. Activate the parking brakes and service brakes. The FRONT BRAKE ON-OFF valve on the instrument panel must be ON.

3. Do the SHIFT SEQUENCE that follows for REVERSE and each FORWARD speed (FIRST, SECOND, THIRD, FOURTH, FIFTH, SIXTH and SEVENTH).

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NOTICE
Check the BRAKE OIL TEMPERATURE gauge regularly. Do not let the brake (torque converter and hoist or wagon hydraulic) oil temperature get too hot during this shift sequence. This can cause damage to the brakes, torque converter, and hoist or wagon hydraulic system. The "T.C./Retarder Oil Temp." indicator on the electronic monitoring panel (EMS), and the master fault light will FLASH when the temperature is too hot to operate in this condition. When the brake (torque converter) oil temperature gets too hot, put the transmission in NEUTRAL and run the engine at approximately 1500 rpm until the temperature returns to the normal operating range.

Shift Sequence:

a. Start and run the engine at LOW IDLE rpm, manually rotate the transmission rotary selector spool to the desired speed. After the manual shift is made, move away from the machine.

b. Gradually increase engine rpm to approximately 1300 rpm or until the machine starts to pull through the brakes, whatever happens first.

c. Look at the rear end of the drive shaft. When there is correct transmission clutch operation, only a small amount of rotation (less than one complete turn) will be seen, except in NEUTRAL. If the machine starts to pull through the brakes before 1300 rpm, there is no need to look at the drive shaft.

d. Decrease the engine rpm to LOW IDLE. Shift to the next speed position. Do Steps a, b, and c of the shift sequence again. This will help in the identification of a slipping (partially engaged) clutch. Continue this sequence for the remainder of the speeds until SEVENTH speed is made.

PROBLEM 1:

The machine starts to creep (move) forward before engine rpm gets to 1300 rpm.

PROBABLE CAUSE:

a. Brake System. See AIR SYSTEM AND BRAKES.

PROBLEM 2:

The drive shaft turns in one or more speeds other than NEUTRAL, but the wheels do not turn. (Clutch or clutches not engaging in transmission.)

PROBABLE CAUSE:

a. See TROUBLESHOOTING THE TRANSMISSION HYDRAULIC SYSTEM, do Visual Checks.

PROBLEM 3:

The drive shaft does NOT turn in NEUTRAL.

PROBABLE CAUSE:

a. See TROUBLESHOOTING THE TORQUE CONVERTER HYDRAULIC SYSTEM, do Visual Checks.

PROBLEM 4:

When a shift is made to REVERSE or any FORWARD speed, the engine stops running.

PROBABLE CAUSE:

a. See TROUBLESHOOTING THE TORQUE CONVERTER HYDRAULIC SYSTEM, do Visual Checks.

PROBLEM 5:

The transmission will not stay in the manually shifted (selected) speed position. Manual shifts are hard in any direction (upshift or downshift).

PROBABLE CAUSE:

a. Solenoid Leakage - shifts to a higher speed (bad upshift solenoid.

- shifts to a lower speed (bad downshift solenoid).

Check 13:

This check will show if the lockup clutch and solenoid valve group operates (the correct pressure is available for the lockup clutch).

PROCEDURE:

1. The jumper wire must still be connected from Socket 1 to Socket 5 of the transmission control harness connector plug.

PRESSURE TAP FOR LOCKUP CLUTCH (WITH PRESSURE GAUGE)

JUMPER WIRE AT THE TRANSMISSION CONTROL HARNESS CONNECTOR (FROM SOCKET 1 TO SOCKET 5)

2. Connect a 4000 kPa (600 psi) pressure gauge to pressure tap for the lockup clutch.

3. Manually shift the transmission to NEUTRAL. Start and run the engine at LOW IDLE rpm.

4. Touch the lockup solenoid chassis harness connector to the solenoid. Each time the connector touches the solenoid, the pressure on the gauge must read approximately 1515 kPa (220 psi).

PROBLEM 1:

The pressure on the gauge IS 0 kPa (0 psi) at all times.

PROBABLE CAUSE:

a. See TROUBLESHOOTING THE TORQUE CONVERTER HYDRAULIC SYSTEM, do Lockup Clutch Tests.

PROBLEM 2:

The pressure on the gauge is not correct when the solenoid is activated.

PROBABLE CAUSE:

a. See TROUBLESHOOTING THE TORQUE CONVERTER HYDRAULIC SYSTEM, do Lockup Clutch Tests.

PROBLEM 3:

The pressure on the gauge is NOT 0 kPa (0 psi) when the lockup solenoid is NOT activated.

PROBABLE CAUSE:

a. See TROUBLESHOOTING THE TORQUE CONVERTER HYDRAULIC SYSTEM, do Lockup Clutch Tests.

Check 14:

This check will show if:

a. The transmission hydraulic controls operate in FIRST speed.

b. No. 2 and No. 6 clutches engage in the transmission in FIRST speed.

PROCEDURE:

1. Remove the jumper wire from the cab harness at the transmission control. Connect the cab harness to the transmission control and the chassis harness to the solenoids (upshift, downshift, and lockup).

2. With the engine at LOW IDLE rpm, and the parking and service brakes engaged, put the transmission shift lever in FIRST speed position. The engine must decrease in rpm. There will be a jerk (movement of the machine forward) when the clutches engage. Also, a change will be heard in the sound of the engine (as the engine picks up load).

3. The transmission control lights (LED's) must be as shown.

PROBLEM 1:

The GEAR lights on the transmission control ARE NOT as shown above. Engine does not decrease in rpm. Engine does not pick up load. (The transmission does not shift into FIRST SPEED).

PROBABLE CAUSE:

a. The rotary actuator is bad. Disassemble the rotary actuator of the transmission hydraulic controls. Check for foreign material, worn or damaged parts.

PROBLEM 2:

The solenoid lights (UPSHIFT and DOWNSHIFT) on the transmission control alternately FLASH (looks like both FLASH at the same time).

PROBABLE CAUSE:

a. Open (floating) ground wire (202-BK) in chassis or cab harness from Pin or Socket 12 of the 20 pin connector to vehicle ground (in the cab). See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

Check 15:

This check will show if:

a. The transmission hydraulic controls operate in REVERSE position.

b. No. 3 and No. 7 clutches engage in the transmission in REVERSE position.

PROCEDURE:

1. With the engine at LOW IDLE rpm and the parking and service brakes engaged, put the transmission shift lever in REVERSE position. The engine must decrease in rpm. There will be a jerk (movement of the machine backward) when the clutches engage. Also, a change will be heard in the sound of the engine (as the engine picks up load).

2. The transmission control lights (LED's) must be as shown.

PROBLEM 1:

The transmission does not shift into REVERSE. (In REVERSE, GEAR the lights on the transmission control ARE NOT correct. Engine does not decrease in rpm. Engine does not pick up load.)

PROBABLE CAUSE:

a. The rotary actuator is bad. Disassemble the rotary actuator of the transmission hydraulic controls. Check for foreign material, worn or damaged parts.

PROBLEM 2:

The solenoid lights (UPSHIFT and DOWNSHIFT) on the transmission control alternately FLASH (looks like both FLASH at the same time).

PROBABLE CAUSE:

a. Open (floating) ground wire (202-BK) in chassis or cab harness from Pin or Socket 12 of the 20 pin connector to vehicle ground (in the cab). See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

Check 16:

This check will show if:

a. The retarder switch activates the transmission control.

b. The retarder activates the rear brakes.

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Sudden movement of the machine can cause injury to persons on or near the machine. To avoid possible injury, never engage the retarder as a secondary or parking brake. The retarder brake system was not designed for a secondary or parking brake condition.

PROCEDURE:

1. With the engine at the MINIMUM GOVERNOR SETTING (LOW IDLE), activate the service brakes (push and hold the brake pedal down).

2. Put the transmission shift lever in FIRST speed position.

3. Engage the brake retarder lever (pull lever toward the operator).

4. Release the parking brakes.

5. Slowly release the brake pedal. The machine must not move under power.

6. Check the RETARDER BRAKE light (LED) on the transmission control. The light must be ON.

7. Slowly increase the engine speed to approximately 1300 rpm. The machine must still not move under power.

PROBLEM 1:

The machine moves under power when the brake pedal and parking brakes are released. The RETARDER BRAKE light on the transmission control is ON.

PROBABLE CAUSE:

a. Brake system. See AIR SYSTEM AND BRAKES.

PROBLEM 2:

The machine moves under power when the brake pedal and parking brakes are released. The RETARDER BRAKE light on the transmission control is OFF.

PROBABLE CAUSE:

a. Brake system. See AIR SYSTEM AND BRAKES.

PROBLEM 3:

The machine does not move under power when the brake pedal and parking brakes are released. The RETARDER BRAKE light on the transmission control is OFF.

PROBABLE CAUSE:

a. Electrical system. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

Check 17:

This check will show if:

a. The retarder switch deactivates (made not active) the transmission control.

b. The retarder deactivates (made not active) the brakes, and the machine will move under power.

PROCEDURE:

1. The transmission shift lever must still be in FIRST speed position.

2. With the engine still at approximately 1300 rpm and the retarder engaged, slowly deactivate (make not active) the retarder lever (push lever away from operator).

3. The machine will move under power when the retarder is deactivated (made not active), and the RETARDER BRAKE light (LED) on the transmission control must be OFF.

NOTE: With the service brakes, parking brakes and retarder OFF, the RETARDER BRAKE light (LED) on the transmission control must be OFF. As the machine moves approximately 2 to 3 mph the speed pickup light must turn (go) OFF.

4. When this check is finished, turn engine off with transmission still in FIRST speed. Activate the parking brakes.

PROBLEM 1:

The machine does not move under power when the retarder is deactivated (made not active). The RETARDER BRAKE light (LED) on the transmission control is OFF.

PROBABLE CAUSE:

a. Brake system. See AIR SYSTEM AND BRAKES.

b. See TROUBLESHOOTING THE DIFFERENTIAL and FINAL drives.

PROBLEM 2:

The machine does not move under power when the retarder is deactivated (made not active). The RETARDER BRAKE light (LED) on the transmission control is ON.

PROBABLE CAUSE:

a. Brake system. See AIR SYSTEM AND BRAKES.

b. See TROUBLESHOOTING THE DIFFERENTIAL and FINAL drives.

PROBLEM 3:

The machine moves under power when the retarder is deactivated, but the RETARDER BRAKE (LED) light is ON.

PROBABLE CAUSE:

a. Electrical system. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

Check 18:

This will show if the neutralizer valve operates correctly. If it operates correctly, the machine will not move when started in any transmission shift lever position other than NEUTRAL. The machine will move when the transmission shift lever is put in the NEUTRAL position and then into a REVERSE or FORWARD position.

PROCEDURE:

1. Engage parking brakes.

2. With the engine OFF, manually move transmission rotary selector spool to the SEVENTH GEAR position.

3. Disconnect the downshift solenoid harness connector from the solenoid.

4. Put the transmission shift lever in the NEUTRAL position. Start and run the engine at the minimum governor setting (low idle).

5. Activate the service brakes. Release the parking brakes.

6. Slowly release the service brakes. The vehicle must not move under power.

7. When this check is complete, engage the parking brakes.

8. Stop the engine. Connect the harness to the downshift solenoid.

PROBLEM 1:

The machine moves under power when the service brakes are released.

PROBABLE CAUSE:

a. The neutralizer valve does not operate correctly. Disassemble the selector group of the transmission hydraulic controls. Check for foreign material or worn or damaged neutralizer valve. Make sure the orifice and/or ball check of the neutralizer valve are free of any debris.

Check 19:

This check will show if:

a. The shift lever switch and the transmission switch are in the same positions.

b. The rotary actuator and rotary selector spool have followed the electrical signals and have put the transmission hydraulic controls in NEUTRAL.

PROCEDURE:

1. Put the transmission shift lever in NEUTRAL position.

2. Release the service and parking brakes. When the engine is started, the machine must not move FORWARD or REVERSE under power.

3. Start and run the engine at LOW IDLE rpm.

4. Engage the parking brakes when this check is complete.

PROBLEM 1:

The machine moves with power either FORWARD or REVERSE during the start up.

PROBABLE CAUSE:

a. The upshift and downshift solenoid connectors are reversed (exchanged).

b. See TROUBLESHOOTING THE TRANSMISSION HYDRAULIC SYSTEM, do Test 4.

Check 20:

This check will show the operation of the speed pickup. If the light (LED) does not go out, the signal (electric frequency) from the speed pickup did not get to the transmission control. The transmission control will not be able to shift automatically.

PROCEDURE:

1. Start and run the engine at LOW IDLE rpm.

2. Activate the service brakes and release the parking brakes.

3. Put the transmission shift lever in FIRST speed position.

4. Slowly release the service brakes. As the machine moves FORWARD (approximately 2-3 mph), the SPEED PICKUP light must go OFF. The speedometer must increase as ground speed increases.

PROBLEM 1:

SPEED PICKUP light stays ON, speedometer reads 0 mph when the machine moves.

PROBABLE CAUSE:

a. Electrical system. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

PROBLEM 2:

SPEED PICKUP light is ON, speedometer reads the correct ground speed.

PROBABLE CAUSE:

a. The transmission control is bad.

Check 21:

For machines with torque converter drive and direct drive (lockup) in SECOND speed (776 Tractor and 777 Truck).

This check will show if:

a. The speed pickup operates correctly for automatic upshifts.

b. The transmission hydraulic controls operate during upshifts to SECOND speed.

c. No. 1 and No. 6 clutches engage in the transmission in SECOND speed.

d. The lockup clutch engages.

For machines with torque converter drive and direct drive (lockup) in FIRST speed (772B tractor, 773B truck, 768C tractor, and 769C truck). Start in the procedure at Step 2.

This check will show if the lockup clutch engages.

PROCEDURE:

1. Increase ground speed (governor setting) and put the transmission shift lever in SECOND speed position. The transmission will automatically shift into SECOND speed as the ground speed (governor setting) of the machine increases.

2. Increase ground speed until maximum governor setting in the selected speed (see NOTE) is made.

NOTE: For the 776 Tractor and 777 Trucks the selected speed will be SECOND. For the 772B Tractor, 773B Truck, 768C Tractor, and 769C Truck the selected speed will be FIRST.

3. Very slowly engage (activate) the retarder (pull lever toward the operator).

4. When the speed of the machine decreases, the LOCKUP solenoid light (LED) on the transmission control must turn OFF and a jerk will be felt.

For the 776 Tractor and the 777 Truck this jerk must not be the result of a downshift to FIRST speed. The DOWNSHIFT solenoid light (LED) on the transmission control must NOT turn ON during this check, (an indication of a downshift).

Maximum Governor For Selected Speed FIRST

Maximum Governor For Selected Speed SECOND

Retarded For Selected Speed FIRST

Retarded For Selected Speed SECOND

PROBLEM 1:

The LOCKUP solenoid light on the transmission control turns OFF and a jerk is not felt.

PROBABLE CAUSE:

a. Lockup clutch does not engage correctly (slips). See TROUBLESHOOTING THE TORQUE CONVERTER HYDRAULIC SYSTEM, do Lockup Clutch Tests.

PROBLEM 2:

The transmission does not automatically upshift to SECOND speed.

PROBABLE CAUSE:

a. Transmission speed sender. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

PROBLEM 3:

The transmission upshifts but the ground speed of the machine does not increase. The machine coasts (moves without power) until a downshift is made.

PROBABLE CAUSE:

a. See TROUBLESHOOTING THE TRANSMISSION HYDRAULIC SYSTEM, do Test 4.

PROBLEM 4:

Transmission cycles (upshifts and downshifts) and the UPSHIFT and DOWNSHIFT solenoid lights alternately FLASH (looks like both FLASH at the same time).

PROBABLE CAUSE:

a. Open (floating) ground wire (202-BK) in chassis or cab harness from Pin or Socket 12 of the 20 pin connector to vehicle ground (in the cab). See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

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The checks that follow must be done with the machine in motion (movement). To prevent possible injury, the following conditions must be performed: 1. A trained machine operator will be needed. 2. An area is needed that is smooth, level and free of other machines. The area must be long enough to operate the transmission in SEVENTH speed. 3. If an area is not available, the machine must be made so that it will not move under power. Put blocks in front of and behind all wheels, and remove (pull out) both drive axles. (On the 768C and 769C, disconnect the rear drive shaft.) Keep the parking brakes activated. 4. Make sure that the body on a truck is lowered (down on the frame) before the truck is moved.

Check 22:

This check will show if:

a. The speed pickup operates correctly for automatic upshifts.

b. The light (LED) sequence on the transmission control for an upshift from one direct drive (lockup) speed position to another direct drive (lockup) speed position is correct.

c. The transmission hydraulic controls operate during upshifts to FOURTH speed.

d. No. 1 and No. 6 clutches engage in the transmission in SECOND speed.

e. No. 3 and No. 6 clutches engage in the transmission in THIRD speed.

f. No. 1 and No. 5 clutches engage in the transmission in FOURTH speed.

PROCEDURE:

Increase ground speed (governor setting) and put the transmission shift lever in FOURTH speed position. The transmission will automatically shift into FOURTH speed as the ground speed (governor setting) of the machine increases. As the machine shifts from a direct drive (lockup) speed position to another direct drive (lockup) speed position, make note of the solenoid light (LED) sequence on the transmission control. The LOCKUP solenoid light will be ON with the UPSHIFT solenoid light for a short time at the start of a shift. When the shift is complete, the UPSHIFT solenoid light will turn OFF before the LOCKUP solenoid light turns ON.

PROBLEM 1:

The transmission does not automatically upshift.

PROBABLE CAUSE:

a. Transmission speed sender. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

PROBLEM 2:

The LOCKUP solenoid light on the transmission control does not turn (go) OFF.

PROBABLE CAUSE:

a. The transmission control is bad.

PROBLEM 3:

The transmission automatically upshifts but the ground speed of the machine does not increase. The machine coasts (moves without power) until an automatic downshift is made.

PROBABLE CAUSE:

a. See TROUBLESHOOTING THE TRANSMISSION HYDRAULIC SYSTEM, do Test 4.

PROBLEM 4:

Transmission cycles (upshifts and downshifts) and the UPSHIFT and DOWNSHIFT solenoid lights alternately FLASH (looks like both FLASH at the same time).

PROBABLE CAUSE:

a. Open (floating) ground wire (202-BK) in chassis or cab harness from Pin or Socket 12 of the 20 pin connector to vehicle ground (in the cab). See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

Check 23:

This check will show if:

a. The automatic downshifts of the transmission control are correct.

b. The light (LED) sequence on the transmission control for a downshift from one direct drive (lockup) speed position to another direct drive (lockup) speed position is correct.

PROCEDURE:

1. Increase ground speed to the MAXIMUM GOVERNOR SETTING in FOURTH.

2. Put the transmission shift lever in THIRD speed position.

3. Decrease the ground speed (governor setting) of the machine. The transmission will automatically downshift to THIRD speed. As the machine shifts from a direct drive (lockup) speed position to another direct drive (lockup) speed position, make note of the solenoid light (LED) sequence on the transmission control. The LOCKUP solenoid light will be ON with the DOWNSHIFT solenoid light for a short time at the beginning of a shift. When the shift is complete, the DOWNSHIFT solenoid light will turn OFF before the LOCKUP solenoid light turns ON.

PROBLEM 1:

The transmission does not automatically downshift to THIRD speed.

PROBABLE CAUSE:

a. Electrical system. See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

PROBLEM 2:

The LOCKUP solenoid light on the transmission control does not turn (go) OFF.

PROBABLE CAUSE:

a. The transmission control is bad.

PROBLEM 3:

Transmission cycles (upshifts and downshifts) and the UPSHIFT and DOWNSHIFT solenoid lights alternately FLASH (looks like both FLASH at the same time).

PROBABLE CAUSE:

a. Open (floating) ground wire (202-BK) in chassis or cab harness from Pin or Socket 12 of the 20 pin connector to vehicle ground (in the cab). See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

Check 24:

This check will show if:

a. The transmission will operate in all speeds.

b. The clutches engage smoothly in all speeds.

PROCEDURE:

Move the transmission shift lever to the SEVENTH speed position. Increase ground speed (governor setting) until the transmission upshifts to SEVENTH speed.

PROBLEM 1:

The transmission upshifts, but the ground speed does not increase in SIXTH and/or SEVENTH speeds. The machine coasts (moves without power) until a downshift is made.

PROBABLE CAUSE:

a. Brakes drag (do not release completely). See AIR SYSTEM AND BRAKES.

b. See TROUBLESHOOTING THE TRANSMISSION HYDRAULIC SYSTEM, do Visual Checks.

PROBLEM 2:

Transmission does not automatically upshift for SECOND, THIRD, FOURTH, FIFTH, SIXTH, or SEVENTH speeds and the speedometer does not read correctly.

PROBABLE CAUSE:

a. Transmission speed sender. See TROUBLESHOOTING POWER TRAIN ELECTRICAL SYSTEM.

PROBLEM 3:

Transmission does not automatically upshift for SECOND, THIRD, FOURTH, FIFTH, SIXTH or SEVENTH speeds and the speedometer works correctly.

PROBABLE CAUSE:

a. Bad transmission control. See TROUBLESHOOTING POWER TRAIN ELECTRICAL SYSTEM.

PROBLEM 4:

Transmission cycles (upshifts and downshifts) and the UPSHIFT and DOWNSHIFT solenoid lights alternately FLASH (looks like both FLASH at the same time.)

PROBABLE CAUSE:

a. Open (floating) ground wire (202-BK) in chassis or cab harness from Pin or Socket 12 of the 20 pin connector to vehicle ground (in the cab). See TROUBLESHOOTING THE POWER TRAIN ELECTRICAL SYSTEM.

Troubleshooting The Torque Converter Hydraulic System

The troubleshooting for the torque converter hydraulic system is divided into four sections: torque converter, lockup clutch, hoist or wagon and brake cooling. The reason for this is to save time and make it easier to find the correct troubleshooting information.

Make reference to the following warning and pressure tap locations for all checks and tests. If the problem area (torque converter, lockup clutch, hoist or brake cooling) is not known, do the checks and tests in the order they are given. For all tests, the oil must be at normal temperature of operation.

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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, do the procedure that follows before testing and adjusting the torque converter.

1. Move the machine to a smooth horizontal location. Move away from working machines and personnel.

2. Put the transmission shift lever in NEUTRAL position. Stop the engine.

3. Permit only one operator on the machine. Keep all other personnel either away from the machine or in view of the operator.

4. Activate the parking brakes.

PINS INSTALLED IN BODY OF TRUCK

5. On a truck, fully lift the body and install the two pins at the rear of the truck. Disconnect the hoist control linkage as shown (remove the cotter pin and pin).

HOIST CONTROL LINKAGE DISCONNECTED

6. Make sure the transmission rotary selector spool is in NEUTRAL position.

7. Make sure all hydraulic pressure is released before any fitting, hose or component is loosened, tightened, removed or adjusted.

6V3121 Multitach Group.6V4160 Transmission Hydraulic Test Group.

If 6V4160 Transmission Hydraulic Test Group is not available, the tools that follow are needed.

One - 6V3965 Valved Nipple.Two - 6V4143 Valved Couplers.One - 6V3079 Hose.One - 6V4142 Unvalved Nipple.One - 1400 kPa (200 psi) Pressure Gauge.^*One - 4000 kPa (600 psi) Pressure Gauge.^*One - 14 000 kPa (2000 psi) Pressure Gauge. ^*

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^*This gauge must be checked for accuracy before it is used.

TORQUE CONVERTER HYDRAULIC SYSTEM IN DIRECT DRIVE, (Lockup Clutch Engaged), ENGINE RUNNING

1. Lockup solenoid.

2. Selector piston for lockup clutch.

3. Load piston for lockup clutch.

4. Pressure reduction valve.

5. Lockup clutch and solenoid valve group.

6. Modulation reduction valve for lockup clutch.

7. Outlet relief valve for torque converter.

8. Secondary and parking brake valve.

9. Relief valve for parking brake release system.

10. Passage to rear wheel brakes.

11. Inlet relief valve for torque converter.

12. Torque converter.

13. Oil cooler for torque converter and brakes.

14. Oil pump drive.

15. Parking brake release oil filter.

16. Torque converter oil filter.

17. Lockup clutch for the torque converter.

18. Screen.

19. Parking brake release section of oil pump.

20. Torque converter charging section of oil pump.

21. Torque converter scavenge section of oil pump.

22. Scavenge screen.

23. Left rear wheel brake.

24. Right rear wheel brake.

25. Hydraulic oil tank.

26. Return oil screen for torque converter and brake cooling.

27. Oil pump for hoist or wagon hydraulics and rear brake cooling.

28. Suction screen.

29. Oil cooler relief valve for rear brakes.

30. Control valve for hoist or wagon hydraulics.

31. Return oil screen for hoist or wagon hydraulics.

32. Suction screen.

P. Pressure tap for pilot oil.

R, V. Pressure taps for parking brake release oil.

S. Pressure tap for torque converter lockup clutch.

T. Pressure tap for torque converter outlet.

U, X, Y, Z, AA, BB. Pressure taps for brake cooling.

W. Pressure tap for torque converter inlet.

Location Of Pressure Taps

LEFT REAR SIDE OF TORQUE CONVERTER
P. Pressure tap for pilot oil (RV). R. Pressure tap for parking brake release oil (PMP). S. Pressure tap for torque converter lockup clutch (LU). T. Pressure tap for torque converter outlet. W. Pressure tap for torque converter inlet.

RIGHT SIDE OF ENGINE
U. Pressure tap for brake cooling (cooler outlet). X. Pressure tap for brake cooling (cooler inlet).

FRONT OF RIGHT REAR WHEEL BRAKE
AA. Pressure tap for brake cooling (inlet). BB. Pressure tap for brake cooling (outlet).

FRONT OF LEFT REAR WHEEL BRAKE
Y. Pressure tap for brake cooling (inlet). Z. Pressure tap for brake cooling (outlet).

Troubleshooting The Torque Converter Hydraulic System When The Oil Gets Too Hot (Overheating Conditions)

INSTRUMENT PANEL

An overheating problem in the hydraulic system will probably be seen first through the warning system. The BRAKE OIL TEMPERATURE gauge and the T.C./RETARDER OIL TEMP. indicator both sense (feel) the temperature of torque converter outlet oil.

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NOTICE
Check the BRAKE OIL TEMPERATURE gauge regularly. Do not let the brake (torque converter and hoist or wagon hydraulic) oil temperature get too hot during this shift sequence. This can cause damage to the brakes, torque converter, and hoist or wagon hydraulic system. The T.C./RETARDER OIL TEMP. indicator on the electronic monitoring panel (EMS), and the master fault light will FLASH when the temperature is too hot to operate in this condition. When the brake (torque converter) oil temperature gets too hot, put the transmission in NEUTRAL and run the engine at approximately 1500 rpm until the temperature returns to the normal operating range.

Problem 1:

The BRAKE OIL TEMPERATURE gauge gives the indication that oil temperature is too hot. The T.C./RETARDER OIL TEMP. indicator is OFF.

PROBABLE CAUSE:

a. See OPERATOR'S STATION AND ELECTRICAL SYSTEM.

Problem 2:

The BRAKE OIL TEMPERATURE gauge gives the indication that oil temperature is NOT too hot. The T.C./RETARDER OIL TEMP. indicator is ON.

BRAKE OIL TEMPERATURE GAUGE

NOTE: The T.C./RETARDER OIL TEMP. indicator activates (comes ON) at approximately 124° C (255° F). The indicator stays activated (keeps ON) until the oil temperature decreases to approximately 110° C (230° F). Therefore it is possible for the BRAKE OIL TEMPERATURE gauge to indicate that oil temperature is NOT too hot while the T.C./RETARDER TEMP. indicator is activated (ON).

PROBABLE CAUSE:

a. See OPERATOR'S STATION AND ELECTRICAL SYSTEM.

Problem 3:

The BRAKE OIL TEMPERATURE gauge gives the indication that oil temperature is too hot. The T.C./RETARDER OIL TEMP. indicator is ON.

Probable Cause:

a. Operate the machine again. Make sure that engine rpm does not get below 1700 rpm. This will make sure enough oil goes through the torque converter and brake oil coolers to keep the oil at normal operating temperature.

Reference: See the OPERATION GUIDE for trucks and tractors for correct operating techniques of the brake system.

Problem 4:

The conditions in PROBLEM 3 are still the same after the machine is operated again.

USE A WIRE TO CHECK FOR A RESTRICTION IN THE INLET TUBE
74. Inlet tube.

PROBABLE CAUSE:

a. To easily see if there is a restriction in the system, remove the cover from the makeup oil tank for the brake hydraulic system.

b. Use a wire as shown to check for a restriction in inlet tube (74). Remove the wire. If there is a restriction, see Problem 5.

EXAMPLE OF OIL FLOW AT LOW IDLE RPM

c. Start and run the engine at LOW IDLE rpm in NEUTRAL. There must be a constant flow of oil (as shown) from inlet tube (74) into the makeup oil tank.

d. Increase engine rpm to HIGH IDLE. The flow of oil must increase as shown.

EXAMPLE OF OIL FLOW AT HIGH IDLE RPM

Problem 5:

There is a restriction in inlet tube (74).

PROBABLE CAUSE:

a. Do Visual Check 5 and use the wire again to check for a restriction.

REMOVE RETURN OIL SCREEN AND CHECK FOR A RESTRICTION IN THE INLET TUBE

Problem 6:

Little or no oil comes out of inlet tube (74).

PROBABLE CAUSE:

There is not enough oil flow in the brake cooling system because of:

a. Failure of oil pump (27) for the hoist or wagon hydraulics. Do Operational Check 6.

b. Failure of torque converter charging section (20) or inlet relief valve (11) for the torque converter is stuck (held) open. Do Torque Converter Test 1.

c. Restriction in screen (18). Do Visual Check 7.

d. Tube joint assembly (flexible coupling) (75) is not installed correctly. Do Visual Check 8.

e. Oil cooler relief valve (29) is set too low. Bench test the oil cooler relief valve to see if it is adjusted correctly.

INSIDE OF HYDRAULIC OIL TANK
29. Oil cooler relief valve. 75. Tube joint assembly.

Visual Checks For The Torque Converter Hydraulic System (Includes Brake Cooling and Hoist or Wagon Hydraulic Systems)

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Make reference to WARNING on the first page of the section TROUBLESHOOTING THE TORQUE CONVERTER HYDRAULIC SYSTEM.

Do Visual Checks first when troubleshooting a problem. Make the checks with the engine OFF and the parking brakes ON. Put the transmission shift lever and transmission rotary selector spool in NEUTRAL. During these checks, use a magnet to separate ferrous particles from non-ferrous particles (O-ring seals, aluminum, bronze, etc.).

Check 1:

Check the oil level in hydraulic oil tank (25). Look for air or water in the oil (at the sight gauge). Many problems in the torque converter are caused by low oil level or air in the oil. Add oil to the hydraulic oil tank if it is needed. The torque converter (hoist or wagon and brake cooling) hydraulic system uses SAE 10W oil.

OUTER RIGHT SIDE OF MAIN FRAME
15. Parking brake release oil filter.

NOTE: Parking brake release oil filter (15) and torque converter oil filter (16) each have an oil filter bypass valve. An oil filter bypass valve lets oil bypass (go around) the oil filter element(s) whenever the pressure difference between inlet oil and outlet oil at the oil filter gets too high. Any oil that does not go through the filter element(s) goes directly into the hydraulic circuit. Dirty oil causes restrictions in valve orifices, sticking valves, etc.

The pressure setting of the bypass valve in both filters is approximately 250 kPa (36 psi).

INNER RIGHT SIDE OF MAIN FRAME
16. Torque converter oil filter.

Problem 1:

The oil level is too high.

PROBABLE CAUSE:

a. Worn or damaged engine crankshaft rear seal lets engine oil into the torque converter cover.

Problem 2:

There is an indication of water in the oil.

PROBABLE CAUSE:

a. Failure of oil cooler (13).

Problem 3:

There is an indication of air in the oil.

PROBABLE CAUSE:

a. Do Visual Check 2.

Problem 4:

The oil level is too low.

PROBABLE CAUSE:

a. Do Visual Check 2. Add oil before any tests are done.

b. Check the oil level in each final drive. Brake cooling oil can leak into the final drive. See Visual Check 1 in the section TROUBLESHOOTING THE DIFFERENTIAL AND FINAL DRIVES.

Check 2:

Inspect all oil lines, hoses and connections for damage or leaks. Look for oil on the ground under the machine.

NOTE: If oil can leak out of a fitting or connection, air can leak in. Air in the system can be as bad as not enough oil.

Check 3:

Remove and inspect (cut apart if necessary) parking brake release oil filter (15) for foreign material.

Problem 1:

Rubber particles are found.

PROBABLE CAUSE:

a. Seal failure.

b. Hose failure.

Problem 2:

Shiny steel particles are found.

LEFT SIDE OF MAIN FRAME
25. Hydraulic oil tank. 26. Return oil screen.

PROBABLE CAUSE:

a. Mechanical failure of parking brake release section (19) of the oil pump.

Check 4:

Remove and inspect (cut apart if necessary) torque converter oil filter (16) for foreign material.

Problem 1:

Rubber particles are found.

PROBABLE CAUSE:

a. Seal failure.

b. Hose failure.

Problem 2:

Shiny steel particles are found.

PROBABLE CAUSE:

a. Mechanical failure of torque converter charging section (20).

Check 5:

Remove and inspect return oil screen (26) for foreign material.

Problem 1:

Rubber particles are found.

PROBABLE CAUSE:

a. Seal failure.

b. Hose failure.

Problem 2:

Shiny steel particles are found.

PROBABLE CAUSE:

a. Mechanical failure of torque converter scavenge section (21). Do Visual Check 6.

Problem 3:

Pieces of red non-ferrous material (part of brake disc) are found.

PROBABLE CAUSE:

a. Failure of wheel brakes (23) and/or (24).

Problem 4:

Aluminum particles are found.

PROBABLE CAUSE:

a. Do Visual Checks 6 and 7.

BOTTOM OF TORQUE CONVERTER COVER
22. Scavenge screen (inside cover).

Check 6:

Drain the cover (housing) of torque converter (12). Measure the amount of oil removed from the cover. Inspect scavenge screen (22) for foreign material and/or a restriction.

Problem 1:

More than 19 liters (5 U.S. gal.) of oil are drained from the cover.

PROBABLE CAUSE:

a. Restriction in scavenge screen (22).

Problem 2:

More than 19 liters (5 U.S. gal.) of oil are drained from the cover and aluminum particles are found.

PROBABLE CAUSE:

a. Mechanical failure of torque converter (12).

Problem 3:

More than 19 liters (5 U.S. gal.) of oil are drained from the cover. During Visual Check 5, shiny steel particles were found in return oil screen (26).

PROBABLE CAUSE:

a. Mechanical failure of torque converter scavenge section (21).

Problem 4:

Iron or steel chips are found.

PROBABLE CAUSE:

a. Worn flywheel or starter gear on engine. Inspect the starter and flywheel gears.

b. Worn drive or driven gear for torque converter oil pump.

c. Mechanical failure of oil pump drive (14). Drain and inspect the oil pump drive.

Problem 5:

Rubber particles are found.

PROBABLE CAUSE:

a. Seal failure.

b. Hose failure.

Problem 6:

Bronze particles are found.

PROBABLE CAUSE:

a. Worn lockup clutch (17) in torque converter (12).

RIGHT SIDE OF ENGINE
18. Screen (between elbow and block).

Check 7:

Remove and inspect screen (18) for foreign material.

Problem 1:

Rubber particles are found.

PROBABLE CAUSE:

a. Seal failure.

b. Hose failure.

Problem 2:

A large quantity of aluminum particles are found.

NOTE: A small amount of aluminum particles from (wear of) oil pump (27) is normal.

PROBABLE CAUSE:

a. Mechanical failure of oil pump (27). Do Visual Check 8.

b. Mechanical failure of torque converter (12).

Check 8:

Drain the oil from hydraulic oil tank (25). Inspect the bottom of the hydraulic oil tank for debris. Remove and clean suction screens (28) and (32). Remove and inspect return oil screen (31) for foreign material. Make sure that tube joint assembly (75) is installed correctly.

Problem 1:

Rubber particles are found.

PROBABLE CAUSE:

a. Seal failure.

b. Hose failure.

Problem 2:

Shiny steel particles and/or chrome particles are found in return oil screen (31).

PROBABLE CAUSE:

a. Mechanical failure of a hydraulic cylinder and/or rod (look at cylinder rods for scoring, etc.).

Problem 3:

A large quantity of aluminum particles are found in return oil screen (31).

NOTE: A small amount of aluminum particles from (wear of) oil pump (27) is normal.

PROBABLE CAUSE:

a. Mechanical failure of oil pump (27).

COVER REMOVED FROM HYDRAULIC OIL TANK
28. Suction screen (behind plate). 31. Return oil screen. 32. Suction screen (behind plate). 75. Tube joint assembly.

NOTE: If any of the above particles are found during any Visual Check, all components of the torque converter, brake cooling and hoist (or wagon) hydraulic systems must be cleaned. Do not use any damaged parts. Any damaged parts must be removed and new parts installed.

Tests For The Torque Converter

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Make reference to WARNING on the first page of the section TROUBLESHOOTING THE TORQUE CONVERTER HYDRAULIC SYSTEM.

Test 1. Torque Converter Outlet Pressure

This test will show if:

a. Torque converter (12) operates correctly.

b. Outlet relief valve (7) is set correctly.

Procedure:

1. Install the 6V3121 Multitach Group on the engine. The 6V3121 Multitach Group can measure engine rpm by the use of either the photo pickup and reflective tape, or a magnetic pickup or tachometer generator. Special Instruction Form No. SEHS7807 has instructions for its use.

6V3121 MULTITACH GROUP

PRESSURE GAUGE CONNECTED TO PRESSURE TAP (T)

2. At pressure tap (T), connect a hose to the nipple. Connect a pressure gauge [1400 kPa (200 psi)] to the hose.

3. Start and run the engine at LOW IDLE rpm in NEUTRAL.

4. The drive wheels must not turn during a stall test. Make sure that air pressure is at the normal pressure for operation. Put the front brakes on-off valve in the ON position. Engage the parking brakes and the service brakes.

NOTE: If the brakes do not keep the machine from movement, put the machine against a solid object that will not move.

5. Make sure that the brake (torque converter) oil is at normal operating temperature. Check to make sure that HIGH IDLE rpm is correct.

6. Move the transmission shift lever to REVERSE position.

7. SLOWLY increase the engine rpm to MAXIMUM GOVERNOR SETTING. The machine will try to move.

8. The engine rpm must be 1980 ± 65 rpm with the torque converter in a stall condition.

9. The pressure on the gauge must be 410 ± 70 kPa (60 ± 10 psi).

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NOTICE
Do not keep the torque converter in a stall condition for very long periods of time. This will cause the torque converter, engine and brakes to get hot.

10. When this test is complete, put the transmission shift lever in NEUTRAL and stop the engine. Remove the test equipment.

Problem 1:

High idle rpm is correct (Step 5), but stall speed (rpm in Step 7) is too high. Torque converter outlet pressure is correct.

PROBABLE CAUSE:

a. Bad torque converter.

OUTLET RELIEF VALVE FOR TORQUE CONVERTER
76. Spacers.

Problem 2:

Torque converter outlet pressure is too low. The oil gets too hot during normal operation.

Problem 3:

Torque converter outlet pressure is too low.

PROBABLE CAUSE:

a. Do Test 2.

Problem 4:

Torque converter outlet pressure is too high. The oil temperature is not too hot.

PROBABLE CAUSE:

a. The setting of outlet relief valve (7) is too high. Remove spacers (76), see SPACER CHART FOR OUTLET RELIEF VALVE.

Problem 5:

Torque converter outlet pressure is correct. The oil gets too hot during normal operation.

PROBABLE CAUSE:

a. See the section, TROUBLESHOOTING TORQUE CONVERTER HYDRAULIC SYSTEM WHEN THE OIL GETS TOO HOT.

Test 2. Torque Converter Inlet Pressure

This test will show if:

a. Inlet relief valve (11) is open.

b. Inlet relief valve (11) is set correctly.

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NOTICE
Inlet pressure to the torque converter MUST NOT be over 930 kPa (135 psi) with COLD OIL. Higher pressures will damage the torque converter. Adjustment of inlet relief valve (11) must only be done during a bench test.

PRESSURE GAUGE CONNECTED TO PRESSURE TAP (W)
77. Hose assembly to hydraulic tank.

Procedure:

1. Make sure that brake (torque converter) oil is at operating temperature.

2. Disconnect hose assembly (77) from inlet relief valve (11). Block or plug the end of the hose assembly so that oil does not drain out of the hydraulic tank.

3. Install another hose to inlet relief valve (11). Put the other end of this hose in a container (bucket, pan, etc.).

4. At pressure tap (W), remove the plug and install a nipple.

5. With a coupler (and hose if necessary), connect a pressure gauge [1400 kPa (200 psi] to the nipple.

6. Start and run the engine at LOW IDLE rpm in NEUTRAL. Immediately check the container to see if any oil is in it.

7. If there is any oil in the container, stop the engine. See Problem 1.

8. If there is no oil in the container, GRADUALLY increase engine rpm to HIGH IDLE in NEUTRAL. The pressure on the gauge must not be more than 930 kPa (135 psi) at any time.

9. When this test is complete, stop the engine. Remove the test equipment.

Problem 1:

There is oil in the container (coming from the inlet relief valve).

NOTE: Connect hose assembly (77) to the inlet relief valve before Step 8 is done.

PROBABLE CAUSE:

a. Spool is stuck open in relief valve. Disassemble the valve to correct the problem or install a new valve.

b. Inlet relief valve (11) is set too low. Bench test the valve to see if it is adjusted correctly.

Problem 2:

There is no oil in the container. Torque converter outlet pressure [at pressure tap (U)] is too low.

PROBABLE CAUSE:

a. The setting of outlet relief valve (7) is too low. Add spacers (76), see SPACER CHART FOR OUTLET RELIEF VALVE (Test 1).

Problem 3:

Torque converter inlet pressure is too high.

PROBABLE CAUSE:

a. Bench test inlet relief valve (11) to see if it is adjusted correctly.

INLET RELIEF VALVE FOR TORQUE CONVERTER
78. Spacers.

Tests For The Lockup Clutch

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Make reference to WARNING on the first page of the section. TROUBLESHOOTING THE TORQUE CONVERTER HYDRAULIC SYSTEM.

Test 3. Parking Brake Release Pressure

This test will show if:

a. Parking brake release section (19) is good.

b. Relief valve (9) is set correctly.

Procedure:

NOTE: Parking brake release pressure can be checked at either pressure tap (R) or (V).

1. Remove the plug at pressure tap (R) or (V). Install a nipple where the plug was removed.

PRESSURE GAUGE CONNECTED TO PRESSURE TAP (R)

2. With a coupler (and hose if necessary), connect a pressure gauge [14 000 kPa (2000 psi)] to the nipple.

3. With the parking brakes activated, start and run the engine at HIGH IDLE rpm in NEUTRAL. The pressure on the gauge must be 3170 ± 200 kPa (460 ± 30 psi).

INNER RIGHT SIDE OF MAIN FRAME (Earlier Models Shown)
8. Secondary and parking brake valve. 9. Relief valve for parking brake release system.

4. When the test is complete, stop the engine and remove the test equipment.

Problem 1:

Oil pressure is low.

PROBABLE CAUSE:

a. Failure of parking brake release section (19).

b. On earlier machines, the setting of relief valve (9) for the parking brake release system is too low. Add shims (79), see SHIM CHART FOR RELIEF VALVE.

c. On later machines, the setting of relief valve (9) for the parking brake release system is to low. Remove cap (103) and loosen nut (101). Turn threaded rod (102) clockwise to increase pressure. One turn increases the setting approximately 690 kPa (100 psi).

Problem 2:

Oil pressure is too high.

PROBABLE CAUSE:

a. On earlier machines, the setting of relief valve (9) for the parking brake release system is too high. Remove shims (79), see SHIM CHART FOR RELIEF VALVE.

b. On later machines, the setting of relief valve (9) for the parking brake release system is to high. Remove cap (103) and loosen nut (101). Turn threaded rod (102) counterclockwise to decrease pressure. One turn decreases the setting approximately 690 kPa (100 psi).

SECONDARY AND PARKING BRAKE VALVE (EARLIER MACHINES)
9. Relief valve for parking brake release system. 79. Shims.

SECONDARY AND PARKING BRAKE VALVE (LATER MACHINES)
9. Relief valve for parking brake release system. 101. Nut. 102. Threaded rod. 103. Cap.

Test 4. Lockup Clutch Pilot Pressure

This test will show if pressure reduction valve (4) is set correctly.

Procedure:

1. At pressure tap (P), remove the plug and install a nipple.

NOTE: The nipple can be permanently installed at pressure tap (P).

2. With a coupler (and hose if necessary), connect a pressure gauge [4000 kPa (600 psi)] to the nipple.

3. With the parking brakes activated, start and run the engine at LOW IDLE rpm in NEUTRAL. The pressure on the gauge must be 2410 ± 100 kPa (350 ± 15 psi).

4. Stop the engine. After the pressure is set correctly, remove the test equipment.

PRESSURE GAUGE CONNECTED TO PRESSURE TAP (P).

LOCKUP CLUTCH AND SOLENOID VALVE GROUP
4. Pressure reduction valve. 80. Shims.

Problem 1:

Oil pressure is too low.

PROBABLE CAUSE:

a. Add shims (80). See SHIM CHART FOR PRESSURE REDUCTION VALVE.

Problem 2:

Oil pressure is too high.

PROBABLE CAUSE:

a. Remove shims (80). See SHIM CHART FOR PRESSURE REDUCTION VALVE.

Test 5. Lockup Clutch Leakage

This test will show if there are bad seals in lockup clutch (17).

Procedure:

REAR OF TORQUE CONVERTER
81. Fitting for lockup clutch pressure.

1. Remove fitting (81) from pressure tap (S).

2. Start and run the engine at LOW IDLE rpm in NEUTRAL.

3. Measure the amount of oil that comes out of pressure tap (S) in one minute. Install fitting (81) when this check is complete.

Problem 1:

More than 3.8 liter/min (1 U.S. gpm) of oil comes out of pressure tap (S).

PROBABLE CAUSE:

a. Bad seals in the lockup clutch.

Test 6. Lockup Clutch Maximum Pressure

This test will show if:

a. Maximum lockup clutch pressure is correct.

b. The operation of modulation reduction valve (6) is correct.

Procedure:

1. Remove the electrical harness connector from lockup solenoid (1).

PRESSURE GAUGE CONNECTED TO PRESSURE TAP (S)

2. Disconnect the cab harness plug from the transmission control. Put a jumper wire from Socket 1 to Socket 5 of the cab harness plug (for the transmission control). This supplies +24 volts to activate the lockup solenoid.

JUMPER WIRE AT TRANSMISSION CONTROL HARNESS CONNECTION (From Socket 1 to Socket 5)

3. At pressure tap (S), use a coupler (and hose if necessary) and connect a pressure gauge [4000 kPa (600 psi)] to the nipple.

4. With the parking brakes activated, start and run the engine at LOW IDLE rpm in NEUTRAL. The pressure on the gauge must be 0 kPa (0 psi).

5. Look at the pressure gauge and connect the electrical harness to lockup solenoid (1). The pressure on the gauge must be 1500 ± 70 kPa (220 ± 10 psi).

6. Remove the electrical harness connector from the lockup solenoid. The pressure on the gauge must go back to 0 kPa (0 psi).

7. Stop the engine. After the problem is corrected, remove the test equipment.

LOCKUP CLUTCH AND SOLENOID VALVE GROUP
82. Shims. 83. Cover. 84. Selector piston plug. 85. Load piston plug. 86. Spring. 87. Load piston orifice. 88. Shuttle valve. 89. Spring.

Problem 1:

Oil pressure in Step 4 is NOT 0 kPa (0 psi).

PROBABLE CAUSE:

a. Selector piston (2) is stuck (will not go back to its original position).

b. Weak or broken spring (89).

c. Lockup solenoid (1) is bad (leaking).

Problem 2:

Oil pressure in Step 5 IS 0 kPa (0 psi).

PROBABLE CAUSE:

a. Selector piston plug (84) is not installed.

b. Little or no pilot oil. Do Test 4.

c. Incorrect operation of shuttle valve (88).

d. Broken spring (86).

Problem 3:

Oil pressure in Step 5 does not increase above 1100 kPa (160 psi).

PROBABLE CAUSE:

a. Load piston plug (85) is not installed.

b. Load piston orifice (87) is plugged.

c. Selector piston is stuck (will not move).

Problem 4:

Oil pressure in Step 6 decreases slowly; or low pressure remains (stays) in the lockup clutch.

PROBABLE CAUSE:

a. Incorrect operation of shuttle valve (88).

b. Selector piston is stuck (will not move).

Problem 5:

Oil pressure in Step 5 is too low.

PROBABLE CAUSE:

a. Do Test 7.

Problem 6:

Oil pressure in Step 5 is too high.

PROBABLE CAUSE:

a. Do Test 7.

Test 7. Lockup Clutch Primary Pressure

This test will show if lockup clutch pressure is adjusted correctly.

Procedure:

1. Make sure that the electrical harness connector is connected to lockup solenoid (1).

2. Make sure the cab harness plug is removed from the transmission control and the jumper wire is installed from Socket 1 to Socket 5 of the cab harness plug.

3. Remove cover (83) from lockup clutch and solenoid valve group (5).

4. Remove load piston plug (85) and install cover (83) again.

5. At pressure tap (S), use a coupler (and hose if necessary) and connect a pressure gauge [1400 kPa (200 psi)] to the nipple.

6. With the parking brakes activated, start and run the engine at LOW IDLE rpm in NEUTRAL. The pressure on the gauge must be 1100 ± 35 kPa (160 ± 5 psi).

7. Stop the engine. After the pressure is set correctly, remove the test equipment.

LOCKUP CLUTCH AND SOLENOID VALVE GROUP
82. Shims. 83. Cover. 84. Selector piston plug. 85. Load piston plug. 86. Spring. 87. Load piston orifice. 88. Shuttle valve. 89. Spring.

Problem 1:

Oil pressure is 0 kPa (0 psi).

PROBABLE CAUSE:

a. Selector piston plug (84) is not installed.

Problem 2:

Primary pressure is too low.

PROBABLE CAUSE:

a. Add shims (82). See SHIM CHART FOR MODULATION REDUCTION VALVE.

Problem 3:

Primary pressure is too high.

PROBABLE CAUSE:

a. Remove shims (82). See SHIM CHART FOR MODULATION REDUCTION VALVE.

Troubleshooting The Transmission Hydraulic System

Make reference to the following warning and pressure tap locations for all checks and tests of the transmission hydraulic system. If the problem area is not known, do the checks and tests in the order they are given. For all tests, the oil must be at normal temperature of operation.

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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, do the procedure that follows before testing and adjusting the transmission.

1. Move the machine to a smooth horizontal location. Move away from working machines and personnel.

2. Put the transmission shift lever in NEUTRAL position. Stop the engine.

3. Permit only one operator on the machine. Keep all other personnel either away from the machine or in view of the operator.

4. Activate the parking brakes.

5. On a truck, fully lift the body and install the two pins at the rear of the truck. Disconnect the hoist control linkage as shown (remove the cotter pin and pin).

6. Make sure the transmission rotary selector spool is in NEUTRAL position.

7. Make sure all hydraulic pressure is released before any fitting, hose or component is loosened, tightened, removed or adjusted.

PINS INSTALLED IN BODY OF TRUCK

HOIST CONTROL LINKAGE DISCONNECTED

3B7282 Nipple [.125 (1/8) in. NPT X 152 mm (6 in) long].6B6552 Elbow [.125 (1/8) in. NPT].9S1712 Reversible Ratchet [.25 (1/4 in.) sq. drive].9S1743 Extension [4 in. long, .25 (1/4 in.) sq. drive].6V3121 Multitach Group.6V4142 Unvalved Nipple.6V4160 Transmission Hydraulic Test Group.6V6064 or FT1874 Transmission Test Cover.

A minimum quantity of gauges and fittings needed: ^*

Two - 6V4144 Valved Couplers.One - 200 kPa (30 psi) Pressure Gauge.Two - 700 kPa (100 psi) Pressure Gauges.^**Two - 4000 kPa (600 psi) Pressure Gauges. ^**

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^*To save time on tests, use the quantity of gauges and fittings that follow:

16 - 6V4144 Valved Couplers.One - 200 kPa (30 psi) Pressure Gauge.Seven - 700 kPa (100 psi) Pressure Gauges.^**Eight - 4000 kPa (600 psi) Pressure Gauges. ^**

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^**These gauges must be checked for accuracy before they are used.

TRANSMISSION HYDRAULIC SYSTEM IN NEUTRAL, ENGINE RUNNING

33. Charging section of transmission oil pump.

34. Scavenge section of transmission oil pump.

35. Transmission oil filter.

36. Downshift solenoid.

37. Upshift solenoid.

38. Rotary actuator.

39. Selector piston for No. 3 clutch.

40. Load piston for No. 3 clutch.

41. Modulation reduction valve for No. 3 clutch.

42. Pressure control group.

43. Modulation reduction valve for No. 5 clutch.

44. Load piston for No. 5 clutch.

45. Selector piston for No. 5 clutch.

46. Transmission oil tank.

47. Return oil filter.

48. Magnetic screen.

49. Suction screen.

50. Reservoir in transmission case.

51. Modulation reduction valve for No. 4 clutch.

52. Load piston for No. 4 clutch.

53. Selector piston for No. 4 clutch.

54. Priority reduction valve.

55. Neutralizer valve.

56. Rotary selector spool.

57. Selector group.

58. Selector piston for No. 1 clutch.

59. Load piston for No. 1 clutch.

60. Modulation reduction valve for No. 1 clutch.

61. Modulation reduction valve for No. 6 clutch.

62. Load piston for No. 6 clutch.

63. Selector piston for No. 6 clutch.

64. Selector piston for No. 2 clutch.

65. Load piston for No. 2 clutch.

66. Modulation reduction valve for No. 2 clutch.

67. Oil cooler relief valve.

68. Relief valve.

69. Transmission oil cooler.

70. Passage for transmission lubrication.

71. Modulation reduction valve for No. 7 clutch.

72. Load piston for No. 7 clutch.

73. Selector piston for No. 7 clutch.

A. Pressure tap for No. 3 clutch.

B. Pressure tap for No. 1 clutch.

C. Pressure tap for No. 2 clutch.

D. Not used.

E. Pressure tap for No. 5 clutch.

F. Pressure tap for No. 4 clutch.

G. Pressure tap for No. 6 clutch.

H. Pressure tap for No. 7 clutch.

J. Pressure tap for upshift pressure.

K. Pressure tap for downshift pressure.

L. Pressure tap for pump.

M. Pressure tap for pilot oil.

N. Pressure tap for transmission lubrication.

Location Of Pressure Taps

RIGHT SIDE OF TRANSMISSION (Earlier Model Shown) (View From Under Machine)
J. Pressure tap for upshift pressure (UP). K. Pressure tap for downshift pressure (DN). L. Pressure tap for pump (PRESS).

NOTE: Later models have pressure tap (L) on downshift solenoid.

LEFT SIDE OF TRANSMISSION
N. Pressure tap for transmission lubrication.

TOP COVER REMOVED FROM TRANSMISSION
A. Pressure tap for No. 3 clutch. B. Pressure tap for No. 1 clutch. C. Pressure tap for No. 2 clutch. D. Not used. E. Pressure tap for No. 5 clutch. F. Pressure tap for No. 4 clutch. G. Pressure tap for No. 6 clutch. H. Pressure tap for No. 7 clutch. M. Pressure tap for pilot oil.

Visual Checks For The Transmission Hydraulic System

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Make reference to WARNING on the first page of the section TROUBLESHOOTING THE TRANSMISSION HYDRAULIC SYSTEM.

Do Visual Checks first when troubleshooting a problem. Make the checks with the engine OFF and the parking brakes ON. Put the transmission shift lever and transmission rotary selector spool in NEUTRAL. During these checks, use a magnet to separate ferrous particles from non-ferrous particles (O-ring seals, aluminum, bronze, etc.).

Check 1:

Check the oil level in transmission oil tank (46). Look for air or water in the oil (through the sight gauge). Many problems in the transmission are caused by low oil level or air in the oil. Add oil to the transmission oil tank if it is needed. The transmission hydraulic system uses SAE 30W oil.

INNER RIGHT SIDE OF MAIN FRAME
35. Transmission oil filter.

NOTE: There is an oil filter bypass valve on the inlet side of the transmission oil filter. The oil filter bypass will open and let oil bypass (go around) the oil filter element whenever the pressure difference between inlet oil and outlet oil through the oil filter gets above 250 kPa (36 psi). Any oil that does not go through the filter element goes directly into the hydraulic circuit. Dirty oil will cause restrictions in valve orifices, sticking valves, etc.

Problem 1:

There is an indication of water in the oil.

PROBABLE CAUSE:

a. Failure of transmission oil cooler (69).

Problem 2:

There is an indication of air in the oil.

PROBABLE CAUSE:

a. Do Visual Check 2.

Problem 3:

The oil level is too low.

PROBABLE CAUSE:

a. Do Visual Check 2.

Check 2:

Inspect all oil lines, hoses, and connections for damage or leaks. Look for oil on the ground under the machine.

NOTE: If oil can leak out of a fitting or connection, air can leak in. Air in the system can be as bad as not enough oil.

Check 3:

Remove and inspect (cut apart if necessary) transmission oil filter (35) for foreign material.

Problem 1:

Rubber particles are found.

PROBABLE CAUSE:

a. Seal failure.

b. Hose failure.

Problem 2:

Shiny steel particles are found.

PROBABLE CAUSE:

a. Mechanical failure of charging section (33) of the oil pump.

TRANSMISSION OIL TANK
46. Transmission oil tank. 47. Return oil filter.

Check 4:

Remove and inspect (cut apart if necessary) return oil filter (47). Inspect its screen also.

Problem 1:

Rubber particles are found.

PROBABLE CAUSE:

a. Seal failure.

b. Hose failure.

Problem 2:

Shiny steel particles are found.

PROBABLE CAUSE:

a. Mechanical failure of scavenge section (34) of the oil pump.

Problem 3:

Bronze particles are found.

PROBABLE CAUSE:

a. Worn clutches in the transmission.

Problem 4:

Aluminum particles are found.

PROBABLE CAUSE:

a. Worn housings, load pistons or selector pistons in pressure control group (42).

BOTTOM OF TRANSFER GEARS
48. Magnetic screen.

Check 5:

Remove and inspect magnetic screen (48) for foreign material.

Problem 1:

Rubber particles are found.

PROBABLE CAUSE:

a. Seal failure.

b. Hose failure.

Problem 2:

Bronze particles are found.

PROBABLE CAUSE:

a. Worn clutches in the transmission.

Problem 3:

Iron or steel chips are found.

PROBABLE CAUSE:

a. Broken components in transfer gears or transmission.

Problem 4:

Aluminum particles are found.

PROBABLE CAUSE:

a. Worn housings, load pistons or selector pistons in pressure control group (42).

DRAIN PLUG FOR TRANSMISSION CASE

Check 6:

Remove the plug in the bottom of the transmission case. This will drain all of the oil out of the transmission and transfer gears. Measure the total amount of oil removed. Inspect the oil for foreign material.

Problem 1:

More than 26 liters (7 U.S. gal.) of oil are drained from the transmission and transfer gears.

PROBABLE CAUSE:

a. Restriction in magnetic screen (48).

b. Failure of scavenge section (34) of the oil pump.

c. Too much leakage in a clutch or clutches of the transmission.

Problem 2:

Rubber particles are found.

PROBABLE CAUSE:

a. Seal failure.

Problem 3:

Bronze particles are found.

PROBABLE CAUSE:

a. Worn clutches in transmission.

Problem 4:

Iron or steel chips are found.

PROBABLE CAUSE:

Broken components in transmission or transfer gears.

Check 7:

Drain the oil from transmission oil tank (46). Inspect the bottom of the oil tank for debris. Remove and clean suction screen (49).

Problem 1:

Rubber particles are found.

PROBABLE CAUSE:

a. Seal failure.

b. Hose failure.

Problem 2:

Shiny steel particles are found.

PROBABLE CAUSE:

a. Mechanical failure of scavenge section (34) of the oil pump.

Problem 3:

Bronze particles are found.

PROBABLE CAUSE:

a. Worn clutches in the transmission.

Problem 4:

Aluminum particles are found.

PROBABLE CAUSE:

a. Worn housings, load pistons or selector pistons in pressure control group (42).

NOTE: If any of the above particles are found during any Visual Check, all components of the transmission hydraulic system must be cleaned. Do not use any damaged parts. Any damaged parts must be removed and new parts installed.

Tests For The Transmission Hydraulic System

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Make reference to WARNING on the first page of the section TROUBLESHOOTING THE TRANSMISSION HYDRAULIC SYSTEM.

Test 1. Transmission Pump Pressure

This test will show if:

a. Charging section (33) of the transmission oil pump is good.

b. Relief valve (68) is set correctly.

Procedure:

1. At pressure tap (L), use a coupler (and hose if necessary) and connect a pressure gauge [4000 kPa (600 psi)] to the nipple.

2. With the parking brakes activated, start and run the engine at LOW IDLE rpm in NEUTRAL. The pressure on the gauge must be 2725 ± 35 kPa (395 ± 5 psi).

3. Run the engine at HIGH IDLE rpm in NEUTRAL. The pressure on the gauge must be 3210 Max. kPa (495 Max. psi).

4. When this test is complete, stop the engine and remove the test equipment.

PRESSURE GAUGE CONNECTED TO PRESSURE TAP (L) (Earlier Model Shown)

NOTE: Later models have pressure tap (L) on downshift solenoid.

SELECTOR GROUP
68. Relief valve. 90. Spacers.

Problem 1:

Oil pressure is too low.

PROBABLE CAUSE:

a. Failure of transmission oil pump.

b. The setting of relief valve (68) is too low. Add spacers (90), see SPACER CHART FOR RELIEF VALVE. Adjust for LOW IDLE setting.

Problem 2:

Oil pressure is too high.

PROBABLE CAUSE:

a. The setting of relief valve (68) is too high. Remove spacers (90), see SPACER CHART FOR RELIEF VALVE. Adjust for the LOW IDLE setting.

Test 2. Transmission Lubrication Pressure

This test will show if:

a. Oil pressure to the transmission lubrication circuit is good.

b. There is oil flow through oil cooler (69).

c. Oil cooler relief valve (67) is closed.

Procedure:

1. At pressure tap (N), use a coupler (and hose if necessary) and connect a pressure gauge [700 kPa (100 psi)] to the nipple.

PRESSURE GAUGE CONNECTED TO PRESSURE TAP (N)

2. With the parking brakes activated, start and run the engine at LOW IDLE rpm in NEUTRAL. The pressure on the gauge must be a minimum of 4 kPa (.5 psi).

3. Run the engine at HIGH IDLE rpm in NEUTRAL. The pressure on the gauge must be 205 to 310 kPa (30 to 45 psi).

4. When this test is complete, stop the engine and remove the test equipment.

Problem 1:

The transmission pump pressure is correct (Test 1). Transmission lubrication pressure is too low.

PROBABLE CAUSE:

a. Oil cooler relief valve (67) is open.

b. Restriction in oil cooler (69).

c. Too much leakage in the transmission lubrication circuit (bad seals, etc.).

Problem 2:

The oil gets too hot during normal operation.

PROBABLE CAUSE:

a. Too much oil in transmission case. Do Visual Check 6.

b. Restriction in oil cooler (69).

Test 3. Pilot Pressure

This test will show if the operation and setting of priority reduction valve (54) are correct.

Procedure:

NOTE: If Tests 4 and/or 5 are to be done and FT1874 Transmission Test Cover is to be used, do Steps 1 through 6 and go on to the next test. Pilot pressure can be checked while clutch pressures are checked.

TRANSMISSION COVERS
91. Large cover. 92. Small cover.

1. Disconnect the wiring harness from downshift solenoid (36) and upshift solenoid (37).

2. Remove the solenoid guard and large cover (91) from the transmission case.

3. Remove the plug from pressure tap (M).

4. Install a 3B6552 Elbow (94) [.125 (1/8) in. NPT] in pressure tap (M). Connect a 3B7282 Nipple (93) [.125 (1/8 in.) NPT X 152 mm (6 in.) long] with a 6V4142 Nipple to the elbow.

5. Put large cover (91) back on top of the transmission case. To prevent the release (spray) of oil and to keep dirt out, use a piece of plastic or paper along with the cover.

6. Connect a pressure gauge [4000 kPa (600 psi)] to the nipple.

7. Start and run the engine at LOW IDLE rpm in NEUTRAL. Keep the parking brakes activated.

PRESSURE GAUGE INSTALLED AT PRESSURE TAP (M)
93. 3B7282 Nipple. 94. 3B6552 Elbow.

8. The pressure on the gauge must be 1725 ± 70 kPa (250 ± 10 psi).

9. When the test is complete, stop the engine.

SELECTOR GROUP
54. Priority reduction valve. 56. Rotary selector spool. 95. Screen. 96. Spacers. M. Pressure tap for pilot oil.

Problem 1:

The pressure on the gauge is too low.

PROBABLE CAUSE:

a. The setting of priority reduction valve (54) is too low. Add spacers (96), see SPACER CHART FOR PRIORITY REDUCTION VALVE.

Problem 2:

The pressure on the gauge is too high.

PROBABLE CAUSE:

a. The setting of priority reduction valve (54) is too high. Remove spacers (96), see SPACER CHART FOR PRIORITY REDUCTION VALVE.

Problem 3:

The pressure on the gauge is correct, but the pressures at ALL clutches are 0 kPa (0 psi) (Test 4).

PROBABLE CAUSE:

a. The operation of neutralizer valve (55) is not correct. Disassemble selector group (57). Check for foreign material or worn or damaged parts. Make sure the orifice and/or ball check valve of the neutralizer valve are free of any debris.

b. Restriction in screen (95) in rotary selector spool (56).

Problem 4:

The pressure on the gauge is correct, but the pressures at ALL clutches are too low (Test 4).

PROBABLE CAUSE:

a. Restriction in screen (95) in rotary selector spool (56).

Test 4. Maximum Clutch Pressures

This test will show if:

a. Maximum clutch pressures are correct.

b. There is too much oil leakage in a clutch.

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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, do the procedure that follows before Tests 4 and/or 5 are done.

1. Move the machine to a smooth horizontal location. Move away from working machines and personnel.

2. Put the transmission shift lever in NEUTRAL position. Stop the engine.

3. Permit only one operator on the machine. Keep all other personnel either away from the machine or in view of the operator.

4. Activate the parking brakes.

5. On a truck, lift the body and install the two pins at the rear of the truck. Disconnect the hoist control linkage (remove the cotter pin and pin).

6. Make sure the transmission rotary selector spool is in NEUTRAL position.

7. Make sure all hydraulic pressure is released before any fitting, hose or component is loosened, tightened, removed or adjusted.

8. Disconnect the rear drive shaft from the rear of the transmission.

9. Make sure the test cover is installed on the transmission case before any tests are done.

Procedure To Manually Shift The Transmission With The Engine Running (Rear Drive Shaft Disconnected)

This procedure will save time when the transmission is tested. Instead of the use of the transmission shift lever in the operator's station, shifts can be made down on the transmission.

1. Make sure the transmission shift lever is in NEUTRAL position.

2. Disconnect the wiring harness from downshift solenoid (36).

3. With the engine OFF, remove the plug for the rotary selector spool from the left side of the transmission case.

4. Use the .25 (1/4) in. sq. drive extension and ratchet to turn the transmission rotary selector spool. When the ratchet is turned toward the rear of the machine as far as it will go, rotary selector spool (56) is in NEUTRAL position. The order of detent positions from NEUTRAL is REVERSE and FIRST through EIGHTH speeds respectively (EIGHTH is not used on 700 series machines).

Procedure:

NOTE: If FT1874 Transmission Test Cover (98) is used, a gauge can be installed at pressure tap (M) to check pilot pressure. If 6V6064 Transmission Test Cover (97) is used, make sure the plug is installed at pressure tap (M).

TRANSMISSION COVERS
91. Large cover. 92. Small cover.

SMALL COVER REMOVED
97. 6V6064 Transmission Test Cover.

1. Remove small cover (92) from large cover (91) and install 6V6064 Transmission Test Cover (97) in place of the small cover. Use four nuts to hold the test cover in position.

Alternate Step 1. Disconnect the wiring harness from downshift solenoid (36) and upshift solenoid (37). Remove the solenoid guard and large cover (91) from the top of the transmission case. Install FT1874 Transmission Test Cover (98) in place of the large cover. Use four bolts to hold the test cover in position.

2. At pressure taps (A), (B), (C), (E), (F), (G) and (H), connect pressure gauges [4000 kPa (600 psi)] to the nipples as shown.

3. Start and run the engine at LOW IDLE rpm in NEUTRAL.

4. Make a record of the pressures on the gauges.

GAUGES INSTALLED FOR MAXIMUM PRESSURE TEST

36. Downshift solenoid.

98. FT1874 Transmission Test Cover.

A. Pressure tap for No. 3 clutch.

B. Pressure tap for No. 1 clutch.

C. Pressure tap for No. 2 clutch.

E. Pressure tap for No. 5 clutch.

F. Pressure tap for No. 4 clutch.

G. Pressure tap for No. 6 clutch.

H. Pressure tap for No. 7 clutch.

M. Pressure tap for pilot oil.

5. Use the .25 (1/4) in. sq. drive ratchet and extension. Move transmission rotary selector spool (56) to REVERSE position (toward the front of the machine one detent position).

6. Make a record of the pressures on the gauges.

PRESSURE CONTROL GROUP
41, 43, 51, 60, 61, 66 and 71. Modulation reduction valves. 99. Load piston plugs (seven). 100. Shims. A, B, C, E, F, G, H. Pressure taps (also load piston body identification).

7. Manually shift the transmission into all forward speeds and make a record of the pressures on the gauges.

8. With the transmission still in SEVENTH speed, increase the engine rpm to the MAXIMUM GOVERNOR SETTING (HIGH IDLE).

9. Make a record of the pressures on the gauges.

10. Decrease engine rpm to the MINIMUM GOVERNOR SETTING (LOW IDLE) and manually shift the transmission to SIXTH speed. Increase engine rpm again to the MAXIMUM GOVERNOR SETTING. Make a record of the pressures on the gauges.

11. Do Step 10 again in all speeds including REVERSE and NEUTRAL. Make sure to decrease engine rpm before each downshift is made.

12. Stop the engine with the transmission rotary selector spool in NEUTRAL.

13. Make a comparison of the actual maximum clutch pressures with the specifications given in the chart.

14. After the problem is corrected, remove the test equipment.

Problem 1:

Pressures at ALL clutches are 0 kPa (0 psi).

PROBABLE CAUSE:

a. Pilot pressure. Do Test 3.

Problem 2:

Pressures at ALL clutches are too low.

PROBABLE CAUSE:

a. Pilot pressure. Do Test 3.

Problem 3:

Pressure at ONE clutch is 0 kPa (0 psi).

PROBABLE CAUSE:

a. Selector piston plug is not installed.

Problem 4:

Pressure in a clutch does not increase above primary pressure.

PROBABLE CAUSE:

a. Load piston plug not installed.

b. Load piston orifice is plugged.

c. Broken OUTER spring(s) in the modulation reduction valve.

Problem 5:

An additional clutch gets pressure oil in some speeds (too many clutches are engaged).

Problem 6:

Maximum pressure in ONE clutch at HIGH IDLE rpm IS NOT correct, but primary pressure in the SAME clutch IS correct.

PROBABLE CAUSE:

a. Do Test 5.

Problem 7:

Primary pressure in ONE clutch IS NOT correct, but maximum pressure in the SAME clutch at HIGH IDLE rpm IS correct.

PROBABLE CAUSE:

a. Do Test 5.

Problem 8:

Maximum pressure in ONE clutch at HIGH IDLE rpm IS correct, but maximum pressure in the SAME clutch at LOW IDLE rpm IS NOT correct (too low).

PROBABLE CAUSE:

a. Bad seals in a clutch of the transmission.

Problem 9:

Pressure in ONE clutch does not decrease rapidly; or low (approximately primary) pressure remains (stays) in ONE clutch.

PROBABLE CAUSE:

a. Decay orifice is plugged.

b. Drain orifice in rotary selector spool (56) is plugged.

Test 5. Primary Clutch Pressures

This test will show if the clutch pressures are adjusted correctly.

Show/hide table

Make reference to the WARNING given in Test 4.

Procedure:

NOTE: Use the PROCEDURE TO MANUALLY SHIFT THE TRANSMISSION WITH THE ENGINE RUNNING given in Test 4.

Show/hide table

NOTICE
Make sure the rear drive shaft is disconnected at the rear of the transmission or the clutches of the transmission will be damaged.

1. If 6V6064 Transmission Test Cover (97) is used, remove large cover (91) from the top of the transmission case. If FT1874 Transmission Test Cover (98) is used, remove it from the transmission case.

2. Remove seven load piston plugs (99) from their bodies.

3. Put the test cover back in position and install four bolts to hold it in place.

GAUGES INSTALLED FOR PRIMARY PRESSURE TEST

36. Downshift solenoid.

98. FT1874 Transmission Test Cover.

A. Pressure tap for No. 3 clutch.

B. Pressure tap for No. 1 clutch.

C. Pressure tap for No. 2 clutch.

E. Pressure tap for No. 5 clutch.

F. Pressure tap for No. 4 clutch.

G. Pressure tap for No. 6 clutch.

H. Pressure tap for No. 7 clutch.

M. Pressure tap for pilot oil.

4. At pressure taps (A), (B), (C), (E), (F), (G) and (H), connect pressure gauges [700 kPa (100 psi)] to the nipples as shown.

5. Start and run the engine at LOW IDLE rpm in NEUTRAL.

6. Make a record of the pressures on the gauges.

7. Use the .25 (1/4) in. sq. drive ratchet and extension. Move the transmission rotary selector spool to REVERSE position (toward the front of the machine).

8. Make a record of the pressures on the gauges.

9. Manually shift the transmission into all forward speeds and make a record of the pressures on the gauges.

10. Stop the engine with the transmission rotary selector spool in NEUTRAL.

11. Make a comparison of the actual primary clutch pressure with the specification given in the chart for each clutch.

12. After the problem is corrected, remove the pressure gauges and test cover. Install load piston plugs (99).

13. Install large cover (91), small cover (92) and the solenoid guard. Connect the wiring harness to the solenoids.

Problem 1:

Pressure at ONE clutch is 0 kPa (0 psi).

PROBABLE CAUSE:

a. Selector piston plug is not installed.

Problem 2:

Primary pressures at ALL clutches are 0 kPa (0 psi).

PROBABLE CAUSE:

a. Pilot pressure. Do Test 3.

Problem 3:

Primary pressures at ALL clutches are too low.

PROBABLE CAUSE:

a. Pilot pressure. Do Test 3.

Problem 4:

Primary pressure at ONE clutch is too low.

PROBABLE CAUSE:

a. Add shims (100) for the modulation reduction valve of the clutch that has low pressure. See SHIM CHART FOR PRESSURE CONTROL GROUP.

Problem 5:

Primary pressure at ONE clutch is too high.

PROBABLE CAUSE:

a. Remove shims (100) for the modulation reduction valve that has high pressure. See SHIM CHART FOR PRESSURE CONTROL GROUP.

Problem 6:

An additional clutch gets pressure oil in some speeds (too many clutches are engaged).

PROBABLE CAUSE:

a. A selector piston is stuck (will not go back to its original position.

b. Weak or broken INNER spring for the modulation reduction valve.

Problem 7:

Maximum pressure in ONE clutch at HIGH IDLE rpm IS NOT correct, but primary pressure in the SAME clutch IS correct.

PROBABLE CAUSE:

a. Wrong OUTER spring(s) installed in the modulation reduction valve.

b. Weak or broken OUTER spring(s) in the modulation reduction valve.

c. Load piston orifice is plugged.

Problem 8:

Primary pressure in ONE clutch IS NOT correct, but maximum pressure in the SAME clutch at HIGH IDLE rpm IS correct.

PROBABLE CAUSE:

a. Wrong OUTER spring(s) installed in the modulation relief valve.

Troubleshooting The Differential And Final Drives

Visual Checks

Use these Visual Checks as a guide to troubleshooting a problem. Make the checks with the engine OFF and the parking brakes ON. During these checks, use a magnet to separate ferrous particles from non-ferrous particles (O-ring seals, bronze, etc.).

Check 1:

Remove the fill plug and check the oil level in each final drive. Make sure that the drain plug is down (in its lowest position) as shown, when the oil level is checked. Check for oil leakage on the rear tires and wheels. The final drives use SAE 50WCD oil.

DRAIN PLUG AND FILL PLUG FOR A FINAL DRIVE

Problem 1:

The oil level in a final drive is too high. The oil level in the hydraulic oil tank is too low.

PROBABLE CAUSE:

a. Brake cooling oil leaks into final drive. Failure of small Duo-Cone seal at the rear wheel brake. Drain final drive and add new oil after a new seal is installed.

Problem 2:

The oil level in a final drive is too low.

PROBABLE CAUSE:

a. Failure of O-ring seal on final drive housing.

Check 2:

Remove the fill plug and check the oil level in the rear axle housing. Check for leakage under the housing. The differential uses SAE 90W oil.

DRAIN PLUG AND FILL PLUG FOR REAR AXLE HOUSING

Problem 1:

The oil level in the rear axle housing is too high. The oil level in a final drive was too high also (Check 1).

PROBABLE CAUSE:

a. Failure of small Duo-Cone seal at the rear wheel brake. Drain rear axle housing and add new oil after a new seal is installed.

Check 3:

Drain both final drives. Remove the covers to inspect for damaged gears, bearings, etc.

Check 4:

Drain the rear axle housing of differential and bevel gear oil. Remove the fill plug and check the bevel gear and pinion for damage. Look in the bottom of the rear axle housing for metal chips. Lift one rear wheel of the machine off the ground. Turn the wheel forward and backward to check the backlash (free movement) in the differential. See the SPECIFICATIONS for the correct amount of backlash.