Use And Repair Of The 6V3060 Les (Low Emission System) And EGR (Exhaust Gas Recirculation) System Tester{0651} Caterpillar

Use And Repair Of The 6V3060 Les (Low Emission System) And EGR (Exhaust Gas Recirculation) System Tester{0651}

Usage:

The 6V3060 Low Emission System (LES) Tester has been designed to test for correct operation of the LES or the former EGR (Exhaust Gas Recirculation) system on Low Emission 3208 Engines. The tester can be used to test the main components of both systems on either an operating engine (Engine Tests) or with the components removed from the engine (Bench Tests). After the main components of either system have been tested and are known to be operating correctly, identification of other components in either system that are not operating correctly can easily be made.

Comparison Between Systems

The low Emission System and Exhaust Gas Recirculation System have certain differences. These differences are given in the following comparison table.

System Differences

EGR System Tester Conversion

To make conversion of 6V3060 EGR System Tester to the 6V3060 Low Emission System Tester, order the following form numbers and install them as shown below.

1 Form SEES5596 (top of lid)

2 Form SEES5597 (over existing label)

3 Form SEES5598 (inside lid)

NOTE: All owners of 6V3060 EGR System Testers should make this conversion to 6V3060 Low Emission System Testers as shown above.

General Description Of The 6V3060 Les Tester

TEST METHODS: The LES system tester can check the Low Emission System either on an operating engine (Engine Test), or by testing the individual components removed from the engine (Bench Test).
ENGINE TEST: A 3 meter (10 ft.) long test cable is used to connect the tester to the Low Emission System on the engine to be tested.
BENCH TEST: A fixture on the tester can be used to bench test the LES switch covers and controls. Also, the tester has a solenoid energizer circuit for solenoid testing.
TEST LIGHTS: Three lights (light emitting diodes) show the condition of the Low Emission System.
POWER: Power to operate the tester is taken from the engine's 12 volt battery or from an external power supply.
OVERVOLTAGE PROTECTION: An internal circuit gives the tester protection from damage if it is connected to a voltage of more than 16 volts but less than 150 volts.
OVERLOAD PROTECTION: An internal circuit breaker gives the tester protection from short circuits in the test cables or in the Low Emission System being tested.
REVERSE VOLTAGE PROTECTION: The internal circuit breaker also prevents tester damage if power is connected incorrectly to the tester.

Specifications

INPUT POWER: An external, 12 volt dc, 3 amp minimum current source must be used (12 volt battery or power supply).
INPUT VOLTAGE: An input voltage of 11.8 to 16 volts dc must be used. A green light on the front panel of the tester will go on when the tester is operating on the correct voltage. The light will go off if the voltage is not within the correct range.
REVERSE VOLTAGE PROTECTION: The LES tester has protection from reverse input voltage application by automatically opening the internal circuit breaker ON-OFF switch.
OPERATING TEMPERATURE RANGE: -17° to 60°C (0° to 140°F)
STORAGE TEMPERATURE RANGE: -40° to 100°C (-40° to 212°F)
TEST ACCURACY: Switch cover output detectors: Low level = 1.5 volts ± .10 volts, High level = 9.0 volts ± .30 volts
SOLENOID OUTPUT: Two individually controlled power outputs send 9.0 volts ± 1.5 volts at a maximum of 1.5 amps from each output to test the solenoid valves.

Controls And Connections

1. ON-OFF POWER SWITCH

Switch with internal circuit breaker, used to control external power input to the tester. Switch will automatically turn off the power under reverse input power or if current is more than 4 amps.

2. POWER LIGHT (LED)

Shows when power is on to the tester and input voltage is within specification (11.8 to 16 Vdc). Light will not come on if input voltage is outside of this range.

3. SOLENOID SWITCH NO. 1

Permits manual operation of the solenoid connected to the female terminal of the ENGINE TEST CABLE, SOLENOID lead.

4. SOLENOID SWITCH NO. 2

Permits manual operation of the solenoid connected to the male terminal of the ENGINE TEST CABLE, SOLENOID lead.

5. RACK CONTACT LIGHT (LED)

Shows rack contact at full load operation

6. BENCH TEST - ENGINE TEST SWITCH

For selection of either bench test of LES cover (using the test fixture) or engine test (on engine LES test) of LES switch cover and control.

7. LOAD SELECTOR

Used during bench test in place of LES switch on engine.

8. OPEN (low load) LIGHT (LED)

Shows when the recirculation valve of the Low Emission System is open.

9. INTERMEDIATE (medium load) LIGHT (LED)

Shows when the recirculation valve of the Low Emission System is in an intermediate position.

10. CLOSED (full load) LIGHT (LED)

Shows when the recirculation valve of the Low Emission System is closed.

11. BENCH TEST FIXTURE

Holds LES switch cover during bench test and makes electrical contact with the switch contacts.

12. RACK CONTACT CLIP

Connects to rack contact screw on the top of the LES switch cover being bench tested.

13. COVER POWER CONNECTOR (BENCH TEST)

Connects to 6V4099 Power Adapter (input power lead) to send power to the cover being tested.

14. SOLENOID CONNECTOR (BENCH TEST)

Connects to solenoid output lead of the LES control in bench test fixture.

15. ENGINE TEST CABLE 6V4097

Connects tester to the LES on the engine for engine test of Low Emission System.

16. RACK CONTACT CLIP

Clip on engine test cable which connects to the rack contact screw on top of the LES cover on the engine.

17. SOLENOID CONNECTOR

Connects to the lead for the LES solenoids on the engine.

18. LES CONTROL OUTPUT CONNECTOR

Connects to output lead of the LES control on the engine.

19. POSITIVE (+) INPUT POWER CLIP (RED)

Connects to positive terminal of 11.8 to 16 Vdc (3 amp minimum) battery or power supply used for power to the tester.

20. NEGATIVE (-) INPUT POWER CLIP (BLACK)

Connects to the negative or chassis (ground) connection of power source.

21. POWER ADAPTER 6V4099

Power adapter for the LES control. Used to permit the LES control (with ring type terminals) to get power from the tester during bench testing.

22. SOLENOID TEST CABLE 6V4098

Cable used to make a ground (negative) connection during solenoid bench test.

Test Procedures

IMPORTANT: Do not make a diagnosis of problems in the Low Emission System without thorough knowledge of the system. A 3208 Diesel Truck Engine Service Manual that has a section on the low emission engine with LES control gives the necessary information. The manual gives a description of the Low Emission System and its operation in detail.

There are two methods for testing the Low Emission System. The first method is the on-engine test. The other method is the bench testing of individual system components. The section that follows gives a description of both methods.

Les Test On Engine

A Connection Of The Les Tester To The Engine

1. Stop the engine. Put the 6V3060 Tester near the engine on a cool, flat area. Open the cover of the tester.

2. Put POWER ON/OFF switch (1) in the OFF position. Put ENGINE TEST CABLE (2) in position in the "vee" of the engine. Make sure the cable is not in contact with turning parts of the engine and not near hot areas, such as the exhaust manifold.

3. Find fuel shutoff solenoid (3) on the fuel pump. Connect black wire (-) clip (4) to a metal part of the engine near the fuel shutoff solenoid. Connect red wire (+) clip (5) to terminal (6) on the fuel shutoff solenoid. Make sure electrical contact is made with these connections (remove paint if necessary.)

4. Turn on the electrical system power to the engine, but do not start the engine. Make sure the tester SOLENOID ENERGIZER SWITCHES (7) and (8) are in the SOL. NO. 1 and SOL NO. 2 (OFF) positions.

5. Put POWER ON/OFF switch (1) in the ON position. It must go into the ON position with a click and remain there. This switch is an automatic circuit breaker and will move to the OFF position if there is a power overload, such as a short circuit in one of the tester output leads.

6. With POWER ON/OFF switch (1) in the ON position, a green light must come on beside the word "ON". In addition to being a power on indicator, the light also gives an indication of the input voltage. If the input voltage is between 11.8 and 16 volts dc, the light will be on. If the input voltage is outside of this range, the light will be off. Test results outside of this voltage range will not be accurate.

7. If the POWER ON light is off, do not start the test. Use a voltmeter to check the input voltage and find the problem in the engine electrical system. If the light is on, the tester is now ready to test the Low Emission System as shown in the following procedure.

B Testing Les Switch, Les Switch Cover And Control

When using the tester to check the Low Emission System on an engine, the LES switch, switch cover and control must be checked together. If this test shows a problem, the defective component can be found by removing the switch cover and control, then checking the cover with a bench test. If the switch cover and control bench test is acceptable, the problem is probably with the LES switch. Use the following procedure to test the switch, cover and control.

1. Connect the LES tester to the engine as shown in the above topic.

2. Turn off the engine electrical power system. Find the LES switch cover (1) and control (2) on the fuel pump.

3. Pull apart the dual bullet connectors (3) that come from the LES control. Connect the tester's ENGINE TEST CABLE lead that is marked LES CONTROL (EGR COVER) to the connector on the wire connected to the LES switch cover. Connect the ENGINE TEST CABLE lead that is marked SOLENOIDS to the other connector on the engine. This wire goes to the LES solenoids on the side of the engine. Fasten the clip on the wire marked, RACK SWITCH, to the screw on the top of LES switch cover (4). Make sure the clip has metal-to-metal contact with the screw.

4. Make sure SOLENOID ENERGIZER switches (5) and (6) are in SOL. NO. 1 (OFF) and SOL. NO. 2 (OFF) positions. Put ENGINE TEST/BENCH TEST switch (7) in the ENGINE TEST position.

5. After power has been connected to the tester and checked as shown on page 6, turn on the engine electrical system power, but do not start the engine. Check the POWER ON/OFF switch to make sure that it is in the ON position. If this switch is not ON and will not stay ON when moved to that position, there can be a short circuit in the LES switch cover or control. Remove the tester wires and check the cover for shorts with an ohmmeter, or do a bench test on the cover.

6. After the POWER ON/OFF switch is on, and the POWER ON light is on, check to make sure one of the LOW EMISSION VALVE POSITION lights is flashing (going on and off). If at least one of these lights is flashing, do the remainder of the test. If this does not correct the problem, do a bench test on the LES switch cover and control.

7. Start the engine. Test the LES switch cover and control with one of the following methods;

a) No Load Test: Put the transmission in neutral and rapidly increase the speed of the engine to full throttle while checking the LOW EMISSION VALVE POSITION lights (8). The flashing light must move from OPEN to INTERMEDIATE to CLOSED as the engine speed increases. As the engine speed becomes constant at full throttle, the flashing light must move from CLOSED to INTERMEDIATE to OPEN. At the full rack position, RACK CONTACT light (9) must flash.

NOTE: It is not necessary for the RACK CONTACT light to flash in order to have correct LES operation.

b) Load Test: This test can be done by using a dynamometer to put different loads on the engine, or by driving the vehicle to get the low, medium and full load conditions. For the load test, the tester must be moved to a location near the operator so the tester lights can be seen. As the different loads are put on the engine, the light that best describes the load condition of the engine must flash on and off. The RACK CONTACT light must come on and flash when the full rack contacts close at full load (balance point of the engine).

8. If the correct lights do not flash according to the load condition of the engine, remove the LES switch cover and control from the engine and do a bench test on it.

C Testing Solenoids And Actuator On Engine

The 6V3060 Tester can be used to test the remainder of the LES components. These components are: the LES actuator (1), LES actuator shaft (2), LES valve (3), and two solenoids (4). Because the LES actuator is driven by engine oil pressure, the engine must be running during this test. The tester SOLENOID ENERGIZER will be used to control the two solenoids. In this test, the position of either the LES actuator shaft (2) or the LES valve shaft (5) must be looked at.

1. Connect the LES tester to the engine's electrical system as shown on page 6. Put the POWER ON/OFF switch in the OFF position.

2. Find the location of the LES actuator shaft or the slotted shaft of the LES valve as given below. One of these must be in view during the test.

3. The LES actuator shaft is the vertical shaft coming out of the top of the LES actuator cylinder. During the test, this shaft will move up and down to any one of three positions. The position of the shaft must be looked at during the test.

4. If the LES actuator shaft can not be seen, look for the LES valve shaft (5) of the LES valve (3). The position of slot (A) in the shaft must be looked at during the test.

5. Start the engine and let the engine run at low idle during the test. Put the tester POWER ON/OFF switch in the ON position. Make sure the POWER ON light is on. Put the SOLENOID ENERGIZER switches in the positions shown below, and look at the position of either the LES actuator shaft or the LES valve shaft.

6. If the shaft being looked at does not move to all three of the positions shown, the actuator assembly is not operating correctly. Check the actuator assembly. If the problem can not be found, bench test the solenoids to see if they are operating correctly.

Bench Test Of The Low Emission System

A Connection Of The Tester To The Power Source

Before a bench test of any LES component can be made, a power supply must be connected to the 6V3060 Low Emission System Tester as shown in the following procedure.

1. Find a dc power supply or a battery with a voltage supply of between 11.8 and 16 volts dc at a minimum of 3 amps. Check the power supply or battery with a voltmeter before connection to the tester to make sure the voltage is within the correct range. If the voltage is adjustable, set the voltage at approximately 14 volts.

2. Put POWER ON/OFF switch (1) in the OFF position.

3. Remove ENGINE TEST CABLE (2) from the case of the tester. Make sure red (+) wire (3) and black (-) wire (4) are separate from the other wires of cable (2).

4. Connect black (-) wire (4) to the negative (-) terminal of the power source. Connect red (+) wire (3) to the positive (+) terminal of the power source.

5. Make sure that none of the metal on the ends of the wires of cable (2) is in contact with other wires or in contact with any metal surface that is connected to the power source.

6. If necessary, turn on the power from the power supply. Put POWER ON/OFF switch in the ON position. The switch must go into the ON position with a click and stay there. This switch is an automatic circuit breaker and will move to the OFF position if there is a power overload, such as a short circuit in one of the tester leads.

7. With the tester connected to the correct supply voltage and the POWER ON/OFF switch in the ON position, POWER light (5) must be on. If this light is not on, check the supply voltage with a voltmeter to make sure that it is between 11.8 and 16 volts dc. If the POWER light is on, the tester is now ready to test the LES system components as shown in the following procedure.

B Testing Les Switch Cover And Control

1. Put POWER ON/OFF switch (1) in the OFF position.

2. Install LES cover (2) in the BENCH TEST FIXTURE as shown. Make sure the cover is pushed completely down into the fixture and clamp (3) is in position over the switch cover.

3. Connect wires (4) from the LES cover to electronic control (5). Use the dual bullet connector to connect the control to SOLENOID connector (6). On some switch covers, it will be necessary to use the short 6V4099 POWER ADAPTER (7) between the control and COVER POWER connector (8). Connect RACK CONTACT clip (9) to the screw on top of the switch cover. Make sure the clip does not come in contact with the metal switch cover housing.

4. Put BENCH TEST/ENGINE TEST switch (10) in the BENCH TEST position. After the power supply has been connected to the tester, put POWER ON/OFF switch (1) in the ON position.

5. If the POWER ON/OFF switch moves by itself from the ON position, and the green POWER ON light (11) is not on, the electronic control or switch cover has a short circuit and is defective. Remove the cover and control from the tester. If the POWER ON/OFF switch is on and the POWER ON light is on, go on with the test.

6. When bench testing the LES switch cover, LOAD SELECTOR switch (12) must be used in place of the engine-mounted LES switch to manually get the three LES conditions. To test the cover, turn LOAD SELECTOR switch (12) to each of the three positions. At each position of the switch, the corresponding light must flash on and off as an indication of correct LES switch cover operation. If any of the lights flash when the switch is not in the corresponding position, the cover or control is defective.

7. When LOAD SELECTOR switch (12) is in the FULL LOAD position, RACK CONTACT light (13) must flash on and off. If it does not, check the clip on top of the LES switch cover to make sure that it is making contact. If the light still will not come on, the switch cover has an open circuit in the full rack circuit and is defective.

C Testing The Les Solenoid

1. Put POWER ON/OFF switch (1) in the OFF position. Put SOLENOID ENERGIZER switches (2) and (3) in the SOL. NO. 1 and SOL. NO. 2 (OFF) positions.

2. If the solenoid is to be pressure tested, connect to the solenoid inlet an air supply that is kept to a pressure of approximately 689 kPa (100 psi). The solenoid being tested must be at a location near the power source of the tester so the ENGINE TEST CABLE can be used.

3. Find the lead on ENGINE TEST CABLE (4) that is marked SOLENOIDS. Put the connector on the solenoid being tested into the female side of the connector on the wire marked SOLENOIDS. Connect one end of SOLENOID TEST CABLE (5) to bare metal on the end of the solenoid. Connect the clip on the other end of cable (5) to the negative (-) terminal of the power source.

4. Put POWER ON/OFF switch (1) in the ON position. Feel the output port of the solenoid. There must be no air leakage out of this port. Move SOL. NO. 1 switch (2) to the ON position. A sound (click) must be heard as the plunger inside the solenoid moves to the open position. Air must now flow out of the outlet port of the solenoid. Move switch (2) back and forth several times to make sure the solenoid is working correctly. To check the solenoid for small leaks, connect a tube to the outlet port and put the other end of the tube under water. Even a small leak will show air bubbles in the water.

NOTE: Two solenoids can be tested at the same time by connecting the second solenoid wire to the male connector on the SOLENOIDS wire. Another ground wire between the bare metal end of the second solenoid and the negative (-) terminal of the power source must be used. Use SOL. NO. 2 switch (3) to control the second solenoid. Do not connect more than two solenoids to the tester at the same time.

Procedure To Check Operation Of Les Tester

Remove the 6V3060 Low Emission System Tester components and make sure all the components are there.

NOTE: Check for shipping damage to the tester and check for components that are loose or not assembled correctly.

Use a variable dc power supply with a 16 volt, 3 amp minimum output for this procedure.

1. To check the automatic circuit breaker, connect tester (1) to reverse voltage. Connect the RED POWER clip (2) to the negative (-) terminal of power supply (4). Connect the BLACK POWER clip (3) to the positive (+) terminal of power supply (4). Put POWER ON/OFF switch (5) in the OFF position. Turn on POWER supply (4) and adjust to 14 volts. Put POWER ON/OFF switch (5) in the ON position. If the breaker is operating correctly, the switch will automatically move back to the OFF position and the breaker will reset.

2. Turn power supply (4) off and reverse the output connections. Connect the RED POWER clip (2) to the positive (+) terminal and the BLACK POWER clip (3) to the negative (-) terminal.

3. Turn power supply (4) on and adjust to less then 10 volts.

4. Connect a 6V3030 Digital Voltmeter (6) (or equivalent voltmeter) to the output terminal of power supply (4) to read the voltage.

5. Put POWER ON/OFF switch (5) in the ON position; increase the voltage until the green light comes on beside the word "ON". Digital voltmeter (6) should read 11.8 ± 0.3 volts dc.

6. Increase the voltage until the green light just goes off; the voltage should read 16.0 ± 0.3 volts dc on digital voltmeter (6).

7. Adjust power supply (4) to 14 volts.

8. Put BENCH TEST/ENGINE TEST switch (7) in the BENCH TEST position.

9. Put SOLENOID ENERGIZER switches (8) and (9) in the OFF position.

10. Find an LES switch cover (10) and control (11) that are known to work correctly; connect them to the BENCH TEST FIXTURE. See the topic, TESTING LES SWITCH COVER AND CONTROL, for the correct setup procedure.

11. Check to make sure power supply (4) is still at 14 volts. Turn LOAD SELECTOR switch (12) to all three positions. At each position of the switch, the corresponding light must flash on and off. When LOAD SELECTOR switch (12) is in the FULL LOAD position, RACK CONTACT light (13) must flash on and off.

12. To check the ENGINE TEST portion of the tester, 10 volt dc, 0.1 amp, minimum filtered, variable power supply (14) is used, along with power supply (4).

13. Connect the positive (+) terminal of power supply (4) to the female connector of LES CONTROL or EGR COVER cable (15) using 6V4099 Adapter (16). Connect the positive (+) terminal of power supply (14) to the male connector of LES CONTROL or EGR CONTROL cable (15) using a short lead wire (17).

14. Connect the negative (-) output terminals of power supply (4) and (14) together with a short piece of wire.

15. Connect 6V3030 Digital Voltmeter (6) (or equivalent voltmeter) to terminals (18) and (19) of power supply (14).

16. Connect POWER CLIPS (20) and (21) to power supply (4), [red to (+) and black to (-)]. Turn on power supply (4) and POWER ON/OFF switch (5). The voltage of power supply (4) should be 14 volts.

17. Turn on power supply (14) and adjust to 0 volts. The LOAD SELECTOR, FULL LOAD light will be on. (The position of the LOAD SELECTOR switch is not important here.)

18. Increase the voltage of power supply (14) to 1.5 ± 0.1 volts. All the lights of the tester, except the POWER ON light, will be off.

19. Increase the voltage of power supply (14) to 9.0 ± 0.3 volts. The MEDIUM LOAD light will be on.

20. Decrease power supply (14) to 0 volts. Turn off power supplies (4) and (14).

21. Reverse the positive leads from power supplies (4) and (14) to the ENGINE TEST CABLE by connecting the positive (+) lead of power supply (14) to the female connector of the test cable and the positive (+) lead of power supply (4) to the male connector of the test cable.

22. Turn on power supplies (4) and (14). Make sure the POWER ON light is on. The NO LOAD light will be the only LOAD SELECTOR light on at this time.

23. Increase power supply (14) to 1.5 ± 0.1 volts. The NO LOAD light will go off.

24. Increase power supply (14) to 9.0 ± 0.3 volts. The MEDIUM LOAD light will turn on.

25. Disconnect the LES control (EGR COVER) connector (15) and turn off power supply (14).

26. Use two 9N2508 Solenoids (22) to check the solenoid test circuit.

27. Put connector (23) from the solenoid into the female connector of the SOLENOID lead wire of the ENGINE TEST CABLE. Connect the other solenoid connector (24) to the male connector of the solenoid lead wire, using a clip lead wire as shown.

28. Connect solenoids (22) together with one end of 6V4098 SOLENOID TEST CABLE (25). Connect the negative (-) terminal of power supply (4) to the other end of test cable (25).

29. Connect digital voltmeter negative (-) lead (26) to the negative (-) terminal of power supply (4) and connect positive (+) lead (27) to solenoid connector (24). Turn on the SOLENOID ENERGIZER switch that shows a voltage on the digital voltmeter.

30. Turn power supply (4) on and adjust the voltage from 11.5 to 16.3 volts; while making this adjustment, check the digital voltmeter to see that it reads 9.0 ± 1.5 volts.

31. Turn the other SOLENOID ENERGIZER switch on and adjust the supply voltage from 11.5 to 16.3 volts. While making this adjustment, check the digital voltmeter for a 9.0 ± 1.5 volt reading.

NOTE: Both SOLENOID ENERGIZER switches should be on at this time.

32. Disconnect positive (+) lead (27) of digital voltmeter (6) from the solenoid it is connected to and connect it to the connector of the other solenoid. Adjust power supply (4) from 11.5 to 16.3 volts. While making this adjustment, check the digital voltmeter for a 9.0 ± 1.5 volt reading.

33. Turn off the SOLENOID ENERGIZER switch that does not control the solenoid connected to the digital voltmeter. Adjust power supply (4) from 11.5 to 16.3 volts again. The reading should be 9.0 ± 1.5 volts on the digital voltmeter while making this adjustment.

34. Turn power supply (4) off and disconnect all the components attached to the tester and power supply.

Troubleshooting And Repair Of The 6V3060 Low Emission Tester

This section can also be used for repair of the 6V3060 EGR Tester; the electronic circuits are the same.

General Circuit Description

Red battery clip J3 connects to the positive (+) output of a 16 volt dc, 3 amp minimum, variable power supply.

Black battery clip J2 connects to the negative (-) output of the same power supply.

When the POWER ON/OFF switch S1 is in the ON position, power is sent to diode D1. If J2 and J3 are connected backwards, diode D1 will cause a short circuit that will activate the circuit breaker in the POWER ON/OFF switch. This prevents reverse voltage from being applied to the tester circuits.

The correct input power detector circuit has power applied to it at this time at R12 and R13.

The voltage from the power supply is divided by 5.9 by the voltage dividers of R13 and R14. This voltage is at PIN 5 of IC6.

Voltage at PIN 5 of IC6 is compared to 2 volts of constant voltage at PIN 4 of IC6. If the divided voltage at PIN 5 is more than 2 volts (input voltage of more than 11.8 volts), PIN 2 of IC6 will increase to 5 volts.

If PIN 5 is lower than 2 volts, PIN 2 of IC6 will be near 0 volts.

The voltage at PIN 10 of IC6 is the input voltage divided by 8, by R12 and R9. The voltage at PIN 10 of IC6 is compared to 2 volts constant voltage on PIN 11 of IC6. If the voltage at PIN 10 of IC6 is lower than 2 volts (input voltage of less than 16 volts), PIN 13 of IC6 will increase to 5 volts. If PIN 10 of IC6 is more than 2 volts, PIN 13 of IC6 will be near 0 volts.

When PIN 2 and PIN 13 of IC6 are at 5 volts, LED D5 will be on.

The input voltage range that lets the LED D5 come on is 11.8 to 16 volts. For the LES tester to operate correctly, the voltage must be in this range.

Protection of the LES tester from input supply voltages of more than 18 volts, comes from the Over Voltage Protection Circuit of transistors Q8 and Q9.

When input voltages are under 18 volts, transistors Q8 and Q9 turn on because the 18 volt Zener Diode D2 is not conducting. Current is conducted to negative (-) ground by the Zener Diode D2 when the input voltage is over 18 volts.

This turns off transistor Q9 and keeps the input voltage from the two voltage regulators IC7 and IC8. IC7 supplies 5 volts to different integrated circuits and transistors that need 5 volt inputs. IC8 is a regulator used with transistors Q10 and Q11 to supply a 9.5 volt, 2 amp (maximum) signal to the solenoids when the Solenoid Test Circuit is used.

The 6V3060 LES Tester is used to test the electronic control that operates the solenoids on any 3208 Low Emission engine.

The electronic control of the Low Emission System has two components, the LES control (1) and the LES switch cover (2).

The EGR System electronic control (3) is a single component. Both types of controls have male/female, dual bullet output connectors (4) and (5) that connect to the solenoid connector on the engine. The signals that are sent to the solenoids are controlled by the electronic control and the way the contacts of the switch cover are grounded through the switch.

The switch of LES control (1) is located in fuel injection pump (6) and is controlled by the amount of load on the engine. (For further information on the complete description of the system operation, see sections 8 and 9 of 3208 Diesel Truck Engine Service Manual, Form SEBR0514-01.)

When a solenoid is on, the bullet connector solenoid terminal of the LES control will have a voltage of more than 9 volts. When the solenoid is not on, less than 1.5 volts will be at the terminal. The following table shows the voltages of each connector terminal when different loads are put on an engine.

The circuit in the LES tester that uses the above voltages is connected to the LES control. Use the Printed Circuit Board diagram on page 18 and LES Tester Schematic to understand the following information about the circuit.

The dual bullet connector of the electronic control can be connected to two different connectors of the LES (EGR) Tester. If a bench test is to be done, the dual bullet connector J9 on the front panel of the BENCH TEST FIXTURE should be used. For an engine test, use the dual bullet connector J5 of the ENGINE TEST CABLE. The dual bullet connectors J5 and J9 on the ENGINE TEST CABLE and BENCH TEST FIXTURE are both marked LES CONTROL or EGR COVER.

Resistors R10 and R11 are connected by the dual bullet BENCH TEST connector J9 of the EGR COVER. Because the solenoids on the engine cause a load, resistors R10 and R11 are not necessary on the ENGINE TEST CABLE.

NOTE: When performing a BENCH TEST or ENGINE TEST, the BENCH TEST/ENGINE TEST switch S2 must be in the correct test position.

A Solenoid Voltage Comparator Circuits

After the connection of the dual bullet connector has been made, the control outputs will be connected to the SOLENOID VOLTAGE COMPARATOR circuits. The voltage that comes from the female connector of the electronic control to the male connector of LES (EGR) tester is connected to the SOLENOID VOLTAGE COMPARATOR circuit at resistors R20 and R25. The voltage at R25 is compared to a 1.5 volt reference voltage at PIN 6 of IC1B. When the voltage at R25 is more than 1.5 volts, the comparator IC1B output at PIN 1 is increased to 5 volts by resistor R27.

When the voltage at R25 is less than 1.5 volts, the output at PIN 1 is almost at 0 volts. The voltage at R20 is divided by 3 and compared to a constant 3 volts at PIN 4 of IC1A. After the divided voltages at PIN 5 of IC1A becomes more than 3 volts (input to R20 is more than 9 volts), the output of PIN 2 of IC1A will increase to 5 volts by R24. When the divided voltage at PIN 5 of IC1A is less than 3 volts, the output at PIN 2 of IC1A will be near 0 volts. The other solenoid voltage comparator circuits IC1B and IC1C operate in a similar way.

Since there are four voltage comparator outputs and only three LED valve position indicator lights on the tester, a logic circuit is used to find the correct LED to turn on. If the LED driver transistor Q6 is on, LED D8 will be on. If transistor Q5 is on, LED D7 will be on. If transistor Q4 is on, LED D6 will be on. For any transistors to be on, a 5 volt signal must be at the base of the transistors. This 5 volt signal comes from IC5 then moves to the base of the transistors through resistors R38, R39 and R40. For transistor Q4 the signal comes from PIN 9, for Q5 the signal comes from PIN 6 and for Q6 the signal comes from PIN 10. The following table shows the signal that will be at IC5, PINS 9, 6 and 10 for the different arrangements of outputs from comparators IC1A, IC1B, IC1C and IC1D.

NOTE: Any other arrangements from IC1A, IC1B, IC1C or IC1D will cause the LED indicator lights to not be on.

B % Rack Current Comparator Circuit

The % RACK CURRENT COMPARATOR circuit is used when RACK CONTACT Connector J1 or J7 is connected to the rack contact screw of the LES COVER (EGR COVER). When an engine is at full rack, the comparator IC6B is used to turn on the RACK CONTACT LED D4. The engine signals the comparator IC6B when the rack contact screw is grounded.

If the rack contact screw is not grounded, PIN 6 of IC6B will beat a higher voltage than at PIN 7. PIN 1 will then be grounded, which causes transistor Q2 to be off. When the rack contact screw is grounded, PIN 6 of IC6B is decreased to a lower voltage than PIN 7 of IC6B. PIN 1 is then increased to 5 volts. This will cause transistor Q2 to turn on, which will make LED D4 turn on.

C Solenoid Test Circuit

Transistors Q10 and Q11 of the SOLENOID TEST circuit IC8 are used to send power to turn on the solenoids used with a 3208 Low Emission Engine. The SOLENOID TEST circuit sends a 9.5 volt, 2 amp signal, (that connects to the solenoid output J4) when the SOLENOID ENERGIZER switches are on. SOL NO. 1 switch sends the signal to the female connector of the solenoid output and SOL. NO. 2 sends the signal to the male connector. All the other functions of the LES tester will not operate if either of the SOLENOID ENERGIZER switches are on.

D Led Flasher Circuit

The LED FLASHER circuit is used to make all the LED indicator lights flash (turn on and off) except LED D5. All the LED indicator lights flash approximately ten times per second. Inverter IC2 at PIN 15 turns on and off and causes the 10 Hz square wave that makes the LED indicator lights flash. When the correct signals from IC1 are not as indicated in the Valve Position Logic Table, an error signal will be sent to IC4 at PINS 12 and 13. This constant signal turns on PIN 11 of IC4, which causes PIN 15 of IC2 to go off. The CORRECT INPUT POWER LED, D5 will stay on and all other LED indicator lights will go off as a result of this.

Repair Information

If the LES Tester seems to be operating incorrectly, follow the procedure shown under the PROCEDURE TO CHECK OPERATION OF LES TESTER on page 12 of this instruction. If the tester does not operate correctly after following this information, the LES Tester may be returned to the manufacturer for service. A letter should accompany the returned unit indicating the problem and the date of purchase from Caterpillar. Units less than one year old will be repaired under warranty. A fee will be charged for units over one year old. The repair center for the tester is:

The Morey Corporation
2659 Wisconsin Avenue
Downers Grove, Illinois 60515
U.S.A.
Telephone No. - (312) 964-2300