ELECTRONIC LOCOMOTIVE CONTROL SYSTEM IIA Caterpillar

Diagnostic Troubleshooting

Usage:

7.1: Introduction

7.1.1: Status Display

The main electronic governor has an LED display on its front face with a decal that indicates the following status conditions:

Generator UnloadGenerator Load Condition In Self Load ModeGenerator Load Condition In Motoring ModeGenerator Load Condition In Dynamic Braking ModeEngine ShutdownEngine Run With Full Power In Self Load ModeEngine Run With Full Power In Motoring ModeEngine Run With Power Derate In Self Load ModeEngine Run With Power Derate In Motoring ModeEngine Run In Dynamic Brake ModeRegulated WheelslipUnregulated WheelslipCalibrate Rack Sensor Mode (Turn Cal In)Calibrate Rack Sensor Mode (Cal Correct)Calibrate Rack Sensor Mode (Turn Cal Out)

7.1.2: Diagnostic Code Display

This same LED display and decal indicate up to 15 diagnostic conditions as follows:

(No Code No.)-Box DefectCode No. 1-Rack SensorCode No. 2-Speed SensorCode No. 3-Derate ModuleCode No. 4-Personality ModuleCode No. 5-Rack Slew RateCode No. 6-Stuck RackCode No. 7-Not UsedCode No. 8-Generator Current Sense.Code No. 9-Generator Voltage SenseCode No. 10-Low Motor Current SenseCode No. 11-High Differential Motor Current SenseCode No. 12-Not UsedCode No. 13-High Motor Current SenseCode No. 14-Open Circuit Exciter Path

The above status conditions and diagnostic codes are displayed by various (on/off/flashing) combinations of eight LED's. There is a decal on the front face of the main governor box that explains how to interpret the status conditions and diagnostic codes from the LED's.

Multiple diagnostic codes are indicated sequentially at five second intervals. Most fault conditions are self clearing. Some fault conditions are latched in idle and all fault conditions are latched with the engine shutdown.

Some of the LED combinations can have two interpretations. These particular combinations are all associated with "self load" mode and "calibrate rack sensor" mode.

7.1.3: Verification Of A Diagnostic Code

NOTE: It is important to establish that the control is not in "self load" mode or "rack calibrate" mode prior to proceeding with a diagnostic code troubleshooting procedure.

Note the condition of the self load status LED (fourth from the bottom):

If it is off or flashing at a rate greater than 1 Hz, the control is not in self load mode or rack calibrate mode. The displayed code is a diagnostic code. Proceed to "7.2: Diagnostic Code Summary thru 7.14: Code 14-Open Circuit Exciter Path".

If it is on continuously and not displaying diagnostic codes 1, 2, or 4, it is in self load mode and displaying a code other than 1, 2, or 4. The displayed code is a diagnostic code. Proceed to "7.2: Diagnostic Code Summary thru 7.14: Code 14-Open Circuit Exciter Path".

If it is on continuously and displaying diagnostic codes 1, 2, or 4, it may be in either self load mode or rack calibrate mode. Proceed to "7.1.4: Check For Load Test Or Calibrate Mode".

7.1.4: Check For Load Test Or Calibrate Mode

Remove the calibrate plug (2) from the personality module. Check the position of the calibrate switch (1) under the plug. Fully counterclockwise (CCW) is "calibrate" and fully clockwise (CW) is "normal". Calibrate switch should be fully clockwise in the normal position. This will require a small flat blade screwdriver.

Personality Module
(1) Calibrate switch. (2) Calibrate plug (removed).

If the self load LED (fourth from the bottom) is now off or flashing at a rate greater than 1 Hz, the control has now been switched out of rack calibrate mode.

If a diagnostic condition is being displayed, proceed to "7.2: Diagnostic Code Summary thru 7.14: Code 14-Open Circuit Exciter Path". If a diagnostic condition is not being displayed return to normal service.

Measure the DC voltage on TB391-L12 with respect to TB391-R3. Battery voltage is "normal" and zero volts is "self load". If the voltage is zero, there is probably a broken or loose connection in the locomotive electrical system. Locate it and repair it.

If after repair the self load LED (fourth from the bottom) is off or flashing at a rate greater than 1 Hz, the control has been switched out of self load mode.

If the self load LED is still on continuously and diagnostic codes 1, 2 or 4 are being displayed, check the continuity of the mounting group connections between TB391-L12 and J1/J2. Repair any defects found.

If the self load LED is still on continuously and diagnostic codes 1, 2 or 4 are being displayed, there is an internal problem in the main electronic governor box or in the personality module. Proceed to "7.1.5: Determining Defective Component".

7.1.5: Determining Defective Component

Diagnostic Code 4

If diagnostic code 4 is being displayed, attempt to start the engine.

If the engine starts and runs, replace both the main governor box and personality module according to "8.2: Main Governor Box and 8.3: Personality Module".

If the engine fails to start, replace the personality module according to "8.3: Personality Module".

After replacing the personality module, if the self load LED is still on continuously, replace the main governor box according to "8.2: Main Governor Box".

Diagnostic Code 2

If diagnostic code 2 is being displayed, turn off the "local control power" and observe the LED's.

All LED's should come on for 6.67 seconds. If any do not come on replace the main governor box according to "8.2: Main Governor Box".

After 6.67 seconds, note the status of the LED's.

If the self load LED is on continuously, replace the main governor box according to "8.2: Main Governor Box".

If the self load LED is on continuously with code 2, replace the personality module according to "8.3: Personality Module".

Re-energize the control and if the self load LED is on continuously after 6.67 seconds also replace the main governor box according to "8.2: Main Governor Box Replacement".

Diagnostic Code 1

If diagnostic code 1 is being displayed turn off the "local control power" and observe the LED's.

All LED's should come on for 6.67 seconds. If any of them do not come on replace the main governor box according to "8.2: Main Governor Box".

After 6.67 seconds, note the status of the LED's.

If the self load LED is on continuously, replace the main governor box according to "8.2: Main Governor Box".

If the self load LED is on continuously with code 1, replace the personality module according to "8.3: Personality Module".

Re-energize the control and if the self load LED is on continuously after 6.67 seconds, also replace the main governor box according to "8.2: Main Governor Box".

7.2: Diagnostic Code Summary

7.2.1: Introduction

There are 14 diagnostic codes. They fall into two main categories:

* Engine System Defects

* Locomotive System Defects

7.2.2: Engine System Defects

7.2.3: Locomotive System Defects

7.3: Code 1-Rack Sensor

7.3.1: Introduction

This code indicates that the main electronic governing box is not receiving the correct pulse coded signal from the rack sensor.

7.3.2: Probable Cause

* The harness connections between the main electronic governing box and the rack sensor.

* The rack sensor assembly.

* The main electronic box.

* The harness connections between the main electronic governing box and the speed sensor (the speed and rack sensors share the same isolated sensor supply).

* The speed sensor.

7.3.3: Speed Sensor

With the engine shutdown and the control system energized (local control power on), unplug the engine harness connector to the electronic governor speed sensor. Note whether diagnostic code 1 ceases to be displayed.

If diagnostic code 1 continues to be displayed, proceed to "7.3.4: Speed Sensor Harness".

If diagnostic code 1 ceases being displayed, there is a problem with the speed sensor. Replace it according to "8.11: Speed Sensor".

7.3.4: Speed Sensor Harness

With the engine shutdown and the control system energized (local control power on), unplug the locomotive system wires to TB392-L6, TB392-L7 and TB392-L8. Note if diagnostic code 1 ceases to be displayed.

If diagnostic code 1 continues being displayed, proceed to "7.3.5: Rack Sensor Harness".

If diagnostic code 1 ceases being displayed, there is a problem with the speed sensor harness. Refer to the locomotive prints and "4.12: Installation Diagrams (diagrams 15 and 16)".

7.3.5: Rack Sensor Harness

Directly connect the following points with a temporary harness in place of the engine and locomotive harness. Note whether diagnostic code 1 now ceases to be displayed.

Rack Sensor Connector Pin 1-TB392-L3Rack Sensor Connector Pin 3-TB392-L4Rack Sensor Connector Pin 2-TB392-L5

In order to gain access to the rack sensor harness, first remove the cover to the rack sensor box on the left side of the front engine housing.

NOTE: Part of the rack sensor assembly is bolted to the inside of this cover. The cover must be securely taped to the box to ensure the harness part of the rack sensor assembly is not damaged.

If code 1 continues to be displayed proceed to "7.3.6: Electronic Governor Mounting Group Harness".

If code 1 now ceases to be displayed, there is a problem in the locomotive harness or the engine harness. Refer to the locomotive prints and "4.12: Installation Diagrams (11 thru 15)" to troubleshoot the harnesses.

7.3.6: Electronic Governor Mounting Group Harness

Disconnect all battery power to TB391 and TB392. Unplug the J2 connector on the main electronic governing box and check the continuity of the following connections:

J2 Connector Pin 3-TB392-L3J2 Connector Pin 4-TB392-L4J2 Connector Pin 5-TB392-L5J2 Connector Pin 6-TB392-L6J2 Connector Pin 7-TB392-L7J2 Connector Pin 8-TB392-L8

Also check the continuity of the above six connections to Battery positive (+), Battery negative (-) and the locomotive chassis. They should all be open (greater than 2 M Ohms). Make any necessary repairs. If no problem is found proceed to "7.3.7: Rack Sensor/Electronic Governing System".

7.3.7: Rack Sensor/Electronic Governing System

At this point it is conclusive that the problem is in one of the following two components:

* Main electronic governor box

* Rack sensor

It is not possible, with every type of defect, to conclusively determine by field test which of the two components is defective. It is only possible in the case of a limited number of defects. For some of the defects it will be necessary to change the rack sensor as part of the diagnostic procedure. Then, if necessary, change the main electronic governor.

Restore all connections and turn on the battery power to TB391 and TB392.

1. With the engine shut down and the control system energized (local control power on), monitor the DC voltage at TB392-L3 with respect to TB392-L5.

This should be 19 ± 3 volts.

2. If the result in step 1 is OK, replace and calibrate the rack sensor according to "8.9: Rack Position Sensor and 8.15: Rack Position Sensor".

If diagnostic code 1 persists, replace the main electronic governor box according to "8.2: Main Governor Box" in the replacement procedures section.

3. If the results in Step 1 are not OK, remove the locomotive system wires from TB392-L3, TB392-L4 and TB392-L5 and monitor the DC voltage at TB392-L3 with respect to TB392-L5.

This should be 19 ± 3 volts.

4. It the result in Step 3 is OK replace and calibrate the rack sensor according to "8.9: Rack Position Sensor and 8.15: Rack Position Sensor".

If diagnostic code 1 persists, replace the main electronic governor box according to "8.2: Main Governor Box" in the replacement procedures section.

5. If the result in Step 3 is not OK replace the main electronic governor box according to "8.2: Main Governor Box" in the replacement procedures section.

If diagnostic code 1 persists replace and calibrate the rack sensor according to "8.9: Rack Position Sensor and 8.15: Rack Position Sensor".

7.4: Code 2-Speed Sensor

7.4.1: Introduction

This code indicates one of three occurrences:

* The measured engine speed has exceeded 2100 RPM since the engine was last run.

* The main electronic governing box has received a momentary interruption in speed sensor signal.

* The main electronic governing box has received a permanent interruption in speed sensor signal.

7.4.2: Probable Cause

The problem must be in one of the following four areas:

* The rack actuator, rack linkage, fuel system, rack actuator harness or main governor box that caused an overspeed.

* Loose connection or short circuit (either intermittent or permanent) in the speed sensor, speed sensor harness or speed sensor connections to the main governor box.

* Loose connection or short circuit (either intermittent or permanent) in the rack sensor, rack sensor harness or rack sensor connections to the main governor box.

* Ferrous chips magnetically attached to the Speed Sensor Tip.

7.4.3: Determine Whether An Overspeed Occurred

If available, refer to the history log of the locomotive to determine whether an overspeed shutdown occurred at the same time as this diagnostic code 2.

If fitted, note whether the shutdown annunciation panel in the cab is indicating an overspeed shutdown.

If still energized, note whether the overspeed switch in the safety shutdown box is indicating an overspeed shutdown.

If it is determined that an overspeed did occur, there is no problem with the speed sensor. Refer to "6.3; Engine Overspeeds" to investigate the cause of the overspeed.

7.4.4: Permanent Defect

Attempt to start the engine and observe the "SHUTDOWN/POWER DERATE/ENGINE RUN" LED on the front face of the main electronic governor box.

If the problem is intermittent the engine will start. If this occurs proceed to "7.4.4.5: Speed Sensor/Electronic Governing System".

If the problem is permanent the engine will not start and this LED will stay on while the engine is being cranked.

Speed Sensor Or Rack Sensor

Unplug the locomotive system wires to the following points:

* TB392-L3

* TB392-L4

* TB392-L5

NOTE: This will cause a diagnostic code 1 to be displayed. Ignore it.

Attempt to start the engine (it may or may not start) and observe the "SHUTDOWN/POWER DERATE/ENGINE RUN" LED on the front face of the main electronic governor box.

If the LED goes out with the engine cranking there is a problem in the rack sensor, the engine harness connections or the locomotive electrical system for the rack sensor connections. Proceed to "7.4.4.2: Rack Sensor Or Rack Sensor Harness".

If the LED stays on there is not a problem in the speed sensor, the engine harness connections or the locomotive electrical system for the speed sensor connections. Proceed to "7.4.4.3: Speed Sensor Or Speed Sensor Harness".

Rack Sensor Or Rack Sensor Harness

Re-connect the locomotive system wires to the following points:

* TB392-L3

* TB392-L4

* TB392-L5

Unplug the rack sensor from the engine harness.

NOTE: This will cause a diagnostic code 1 to be displayed. Ignore it.

In order to gain access to the rack sensor harness, first remove the cover to the rack sensor box on the left side of the front engine housing.

NOTE: Part of the rack sensor assembly is bolted to the inside of this cover and the cover must be securely taped to the box to ensure the harness part of the rack sensor assembly is not damaged.

Attempt to start the engine (it may or may not start) and observe the "SHUTDOWN/POWER DERATE/ENGINE RUN" LED on the front face of the main electronic governor box.

If the LED goes out with the engine cranking, the problem is in the rack sensor. Replace and calibrate the rack sensor according to "8.9: Rack Position Sensor and 8.15: Rack Position Sensor".

If the LED stays on, the problem is in the engine harness connections or the locomotive electrical system for the rack sensor connections. Refer to the locomotive prints and "4.12 Installation Diagrams (diagrams 11 thru 15) to troubleshoot and isolate the problem. Make necessary repairs.

Speed Sensor Or Speed Sensor Harness

Directly connect the following points with a temporary harness in place of the engine and locomotive harness:

Speed Sensor Connector Pin C-TB392-L6Speed Sensor Connector Pin A-TB392-L7Speed Sensor Connector Pin B-TB392-L8

Attempt to start the engine and observe the "SHUTDOWN/POWER DERATE/ENGINE RUN" LED on the front face of the main electronic governor box.

If the engine starts there is a problem in the engine harness connections or the locomotive electrical system for the speed sensor connections. Refer to the locomotive prints and "4.12: Installation Diagrams (diagrams 11 thru 15") to troubleshoot and isolate the problem. Make necessary repairs.

Electronic Governor Mounting Group Harness

Disconnect all battery power to TB391 and TB392.

Unplug the J2 connector on the main electronic governing box and check the continuity of the following connections:

J2 Connector Pin 3-TB392-L3J2 Connector Pin 4-TB392-L4J2 Connector Pin 5-TB392-L5J2 Connector Pin 6-TB392-L6J2 Connector Pin 7-TB392-L7J2 Connector Pin 8-TB392-L8

Also check the continuity of the above six connections to Battery positive (+), Battery negative (-) and the locomotive chassis. They should all be open (> 2 M Ohms).

Make any necessary repairs.

Speed Sensor/Electronic Governing System

At this point it is conclusive that the problem is in one of the following two components:

* Main electronic governor box.

* Speed sensor.

Restore all connections and turn on the battery power to TB391 and TB392.

1. With the engine shut down and the control system energized (local control power on), monitor the DC voltage at TB392-L7 with respect to TB392-L8. The DC voltage should be 10 ± 2 volts.

2. If the results in step 1 are not OK replace the main electronic governor box according to "8.2: Main Governor Box".

3. If the results in step 1 are OK monitor the DC voltage at TB392-L6 with respect to TB392-L8 with and without the engine cranking. With the engine not cranking this should be either 0 volts or step 1 result + 0/-1 volt. With the engine cranking this should be step 1 result ± 1 volt.

4. If the results in step 3 are OK, replace the main electronic governor box according to "8.2: Main Governor Box".

5. If the results in step 3 are not OK replace the speed sensor according to "8.11: Speed Sensor".

7.5: Code 3-Derate Module

7.5.1: Introduction

This code indicates that the main electronic governing box is not receiving the correct pulse coded signal from the derate module.

7.5.2: Probable Cause

The defect must be in one of the following three areas:

* Loose connection or short circuit in the harness connections between the main electronic governor box and the derate module.

* Internal defect in the derate module.

* Internal defect in the main electronic governor box.

7.5.3: Harness Connections

Disconnect all battery power to TB391 and TB392. Unplug the J1 and J2 connectors on the main electronic governing box and check the continuity of the connections identified in diagram 1. Also check the continuity of these connections to battery positive (+), battery negative (-) and the locomotive chassis. They should all be open (greater than 2 M Ohms). Make any necessary repairs.

Diagram 1

7.5.4: Derate Module Or Main Governor Box

At this point it is conclusive that the problem is in one of the following two components:

* Main electronic governor box.

* Derate module.

There is no methodical field test available for conclusively identifying which of the two components has failed.

Replace the derate module according to "8.4: Altitude Derate Module or 8.5: Non-Altitude Derate Module".

If code 3 is not displayed after turning on the battery power, the derate module had the defect.

If code 3 is continuing to be displayed after turning on the battery power, the main electronic governor box has the defect. Replace the main electronic governor box according to "8.2: Main Governor Box".

7.6: Code 4-Personality Module

7.6.1: Introduction

This code indicates that the main electronic governing box has detected corrupted memory in the personality module.

7.6.2: Probable Cause

* Internal defect in the personality module.

* Internal defect in the main electronic governing box.

7.6.3: Procedure

There is no methodical field test available for conclusively identifying which of the two components has failed.

1. Remove the personality module and inspect the mating electrical connectors on the personality module and main governor box for any obvious damage.

2. If step 1 reveals damage to the connector on the main governor box, replace the main governor according to "8.2: Main Governor Box".

3. If step 1 reveals no damage to the connector on the main governor box, replace the personality module according to "8.3: Personality Module".

4. If code 4 continues to be displayed after step 3 replace the main governor according to "8.2: Main Governor Box".

5. If code 4 indication persists after step 2 replace the personality module according to "8.3: Personality Module".

7.7: Code 5-Rack Slew Rate

7.7.1: Introduction

This code indicates that the main electronic governing box has detected an abnormally high slew rate on the rack position feedback signal from the rack position sensor.

7.7.2: Probable Cause

The problem must be in one of the following areas:

* Problem with the engine oil supply to the rack actuator.

* Internal defect in the rack actuator.

* Internal defect in the main electronic governing box.

* Internal defect in the rack sensor.

* Problem with the emergency shutdown system.

7.7.3: Valid Defect Or Normal Occurrence

This code indicates an event rather than a condition. It will therefore be displayed as a temporary defect rather than a permanent condition. Every code is displayed for a minimum of five seconds. If this code is displayed for approximately five seconds, it indicates that an isolated event has occurred.

Isolated instances of high rack slew rate are normal under any circumstances that would normally produce a rapid change in engine power or rack position. These include:

* Engine start.

* Engine shutdown.

* Severe wheelslip.

Certain defect conditions can produce rapid changes in engine power or rack position without there being a specific defect in the rack actuator, sensor or governor box. These are:

* Intermittent problem with 24T signal scaling.

* Intermittent problem with generator voltage sense scaling.

* Intermittent problem with generator current sense scaling.

* Intermittent problem with motor current sense scaling.

* Erratic engine speed governing.

Normally such defects will accompany other diagnostic codes which should be investigated prior to investigating code 5.

7.7.4: Normal Occurrence

Review the failure report in detail in light of the information in "7.7.3: Valid Defect Or Normal Occurrence" to determine whether the occurrence was due to normal or other circumstances not related to the probable causes listed.

If so ignore and do not attempt any further investigation.

7.7.5: Rack Sensor

1. Run the engine under the conditions that produced diagnostic code 5. If possible, run it at no load.

2. If the engine is unloaded observe the rack actuator lever motion. It should be steady. If it is not the engine speed will be erratic and the investigator should refer to "6.4: Erratic Engine Speed".

If it is steady there is a problem with the rack sensor. Replace and calibrate it according to "8.9: Rack Position Sensor and 8.15: Rack Position Sensor".

3. If the engine has to be loaded in step 1, observe the rack actuator lever motion. It will probably not be steady.

If it is steady, or if the motion is smooth rather than jerky, there is a problem with the rack sensor. Replace and calibrate it according to "8.9: Rack Position Sensor and 8.15: Rack Position Sensor".

If the motion is jerky the rack sensor signal to the main governor box is truly reflecting the jerky motion and the problem is not in the rack sensor.

7.7.6: Oil Supply To Rack Actuator

If there is any problem with the oil supply to the rack actuator it will manifest itself under no load and result in an erratic engine speed. Refer to "6.4: Erratic Engine Speed".

7.7.7: Rack Actuator

If there is any problem with the rack actuator it will manifest itself under no load and result in an erratic engine speed. Refer to "6.4: Erratic Engine Speed".

7.7.8: Main Governor Box

If there is any problem with the main governor box it will manifest itself under no load and result in an erratic engine speed. Refer to "6.4: Erratic Engine Speed".

7.8: Code 6-Stuck Rack

7.8.1: Introduction

This code indicates that the main electronic governing box is driving the rack actuator at its maximum level.

7.8.2: Probable Cause

The problem ust be in one of the following areas:

* Problem with the engine oil supply to the rack actuator.

* Internal defect in the rack actuator.

* Internal defect in the main electronic governing box.

* Excessive harness resistance in the rack actuator drive current path.

* Excessive friction in the rack linkage.

* Link between rack linkage and actuator wrong length.

* SR1 opened in run/stop logic without also giving electronic governor a "D" only code.

7.8.3: Rack Actuator Oil Supply

Refer to "8.29: Actuator Check" to investigate the oil supply to the rack actuator.

7.8.4: Rack Actuator

Electrical Problem

1. Remove the cover to the engine harness pull thru box located on the right hand side of the front engine housing (just behind the rack actuator). This will allow access to TB254.

2. Remove the wires from the rack actuator to TB254-B3 and TB254-B4.

Connect a digital multimeter across the rack actuator leads set to read at least 45 ohms. Note the reading.

The resistance is a function of coil temperature (T°C) as follows:

Resistance = 0.1555×(T°C) + 28.35 ± 1 ohm

3. If incorrect replace the rack actuator.

Mechanical And Hydraulic Problem

Refer to "8.29: Actuator Checkout" to identify any mechanical or hydraulic problems with the rack actuator.

7.8.5: Rack Linkage

Refer to 3500 Locomotive Engines Specifications, SENR4636 to investigate the rack linkage.

7.8.6: Rack Actuator Link

1. Remove the cover to the engine harness pull thru box located on the right hand side of the front engine housing (just behind the rack actuator). This should allow access to TB254.

2. Remove the wire from the rack actuator to TB254-B3 and connect a digital multimeter in series set to read at least 200 milliamps DC full scale.

3. Start the engine and run it at idle speed no load and note the meter reading.

It should be 50 ± 10 milliamps.

4. If step 3 results are not correct shut the engine down and make an adjustment to the length of the rack actuator link. This requires temporary disassembly of the link from the actuator.

Before re-assembly ensure the link is not too short resulting in the rack being above shut-off position with the actuator at its minimum position.

5. Repeat steps 3 and 4 until step 3 results are correct.

7.8.7: Harness Resistance

Engine And Locomotive Harness

1. Remove the cover to the engine harness pull thru box located on the right hand side of the front engine housing (just behind the rack actuator). This should allow access to TB254.

2. Remove the wires from the rack actuator to TB254-B3 and TB254-B4. Connect a digital multimeter across the rack actuator leads set to read at least 45 ohms. Note the reading.

3. Disconnect the meter and re-connect the rack actuator wires to TB254-B3 and TB254-B4.

4. Disconnect the locomotive system wires from TB392-L1 and TB392-L2. Connect a digital multimeter across the locomotive system wires set to read at least 45 ohms.

5. Attempt to start the engine and note the meter reading while the engine is cranking. It should be equal to step 4 result ± 2 ohms.

6. If step 5 results are not correct there is a problem with the rack actuator drive current path. Refer to the locomotive prints and "4.12: Installation Diagrams (diagrams 11 thru 15)" to troubleshoot.

Mounting Group Harness

1. Disconnect all battery power to TB391 and TB392.

2. Unplug the J2 connector from the main electronic governor box.

3. Check between:

J2 Connector Pin 1-TB392-L1

J2 Connector Pin 2-TB392-L2

Also check for short circuits to battery positive (+), battery negative (-) and the locomotive chassis on the above connections. Make any necessary repairs.

7.8.8: Main Governor Box

1. Remove the cover to the engine harness pull thru box located on the right hand side of the front engine housing (just behind the rack actuator). This should allow access to TB254.

2. Remove the wire from the rack actuator to TB254-B3 and connect a digital multimeter in series set to read at least 200 milliamps DC full scale.

3. Start the engine and run it at the condition that caused diagnostic code 6. Note the meter reading.

4. If step 3 results are less than 160 milliamps there is a problem with the main governor box. Replace it according to "8.2: Main Governor Box".

7.9: Code 8-Generator Current Sense

7.9.1: Introduction

This diagnostic code indicates that the main electronic governing box is not receiving a finite generator current sense signal under conditions it would normally be expected to be receiving it.

7.9.2: Probable Cause

* Incorrect generator current sense scale factor.

* Wiring problem in main electronic governing system mounting group.

* Internal defect in main electronic governing box.

7.9.3: Check Scale Factor

Refer to "8.19: Generator Current Sense Scale Factor" for the procedure to measure the scale factor.

If the scale factor is correct proceed to "7.9.5: Check Mounting Group Wiring".

If the scale factor is not correct proceed to "7.9.4: Troubleshoot Wrong Scale Factor".

7.9.4: Troubleshoot Wrong Scale Factor

Refer to "6.22: Incorrect Scaling Of Generator Current Sense" for the procedure to troubleshoot this problem.

7.9.5: Check Mounting Group Wiring

1. Disconnect all battery power to TB391 and TB392.

2. Unplug the J1 connector from the main electronic governor box.

3. Check continuity between:

J1 Connector Pin 10-TB391-L10

J1 Connector Pin 9-TB391-L9

Also check for short circuits to battery positive (+), battery negative (-) and the locomotive chassis on the above connections. Make any necessary repairs.

4. If no repairs were necessary replace the main electronic governor box according to "8.2: Main Governor Box".

7.10: Code 9-Generator Voltage Sense

7.10.1: Introduction

This diagnostic code indicates that the main electronic governing box is not receiving a finite generator voltage sense signal under conditions it would normally be expected to be receiving it.

7.10.2: Probable Cause

* Incorrect generator voltage sense scale factor.

* Wiring problem in main electronic governing system mounting group.

* Internal defect in main electronic governing box.

7.10.3: Check Scale Factor

Refer to "8.18:Generator Voltage Sense Scale Factor" for the procedure to measure the scale factor.

If the scale factor is correct proceed to "7.10.5: Check Mounting Group Wiring".

If the scale factor is not correct proceed to "7.10.4: Troubleshoot Wrong Scale Factor".

7.10.4: Troubleshoot Wrong Scale Factor

Refer to "6.21: Incorrect Scaling Of Generator Voltage Sense" for the procedure to troubleshoot this problem.

7.10.5: Check Mounting Group Wiring

1. Disconnect all battery power to TB391 and TB392.

2. Unplug the J1 connector from the main electronic governor box.

3. Check continuity between:

J1 Connector Pin 11-TB391-L11

J1 Connector Pin 9-TB391-L9

Also check for short circuits to battery positive (+), battery negative (-) and the locomotive chassis on the above connections. Make any necessary repairs.

4. If no repairs were necessary replace the main electronic governor box according to "8.2: Main Governor Box".

7.11: Code 10-Low Motor Current Sense

7.11.1: Introduction

This diagnostic code indicates that the derate module is not receiving a finite low motor current sense signal under conditions it would normally be expected to be receiving it.

7.11.2: Probable Cause

* Incorrect motor current sense scale factor.

* Wiring problem in main electronic governing system mounting group.

* Internal defect in derate module.

7.11.3: Check Scale Factor

Refer to "8.20: Motor Current Sense" for the procedure to measure the scale factor.

If the scale factor is correct proceed to "7.11.5: Check Mounting Group Wiring".

If the scale factor is not correct proceed to "7.11.4: Troubleshoot Wrong Scale Factor".

7.11.4: Troubleshoot Wrong Scale Factor

Refer to "6.23: Incorrect Scaling Of Motor Current Sense" for the procedure to troubleshoot this problem.

7.11.5: Check Mounting Group Wiring

1. Disconnect all battery power to TB391 and TB392.

2. Unplug the J1 connector from the main electronic governor box.

3. Check continuity between:

Derate Module Terminal 7-TB392-R5

Derate Module Terminal 6-TB391-L9

Also check for short circuits to battery positive (+), battery negative (-) and the locomotive chassis on the above connections. Make any necessary repairs.

4. If no repairs are necessary replace the derate module. Refer to the "8.4: Altitude Derate Module or 8.5: Non-Altitude Derate Module" for the correct procedure.

7.12: Code 11-High Differential Motor Current

7.12.1: Introduction

This diagnostic code indicates that the electronic governing system has detected an excessive level of differential motor current. It would be normal for this code to be indicated when there is a low motor current sense diagnostic code 10. On very poor track conditions and with high traction motor currents, it is normal for this code to be displayed occasionally when there is an excessive wheelslip outside the range of normal wheelslip regulation. Diagnostic code 11 should only be investigated when it occurs in the absence of any other diagnostic codes.

7.12.2: Probable Cause

* Incorrect motor current sense scale factor.

* Traction motor problem.

* Mismatched traction motors (one motor is the wrong type).

* Mismatched traction motor gearing (one motor has a different final drive ratio to the others).

* Slipping pinion.

7.12.3: Check Scale Factor

Refer to "8.20: Motor Current Sense" for the procedure to measure the scale factor.

If the scale factor is correct proceed to "7.12.5: Traction Motor Problem".

If the scale factor is incorrect proceed to "7.12.4: Troubleshoot Wrong Scale Factor".

7.12.4: Troubleshoot Wrong Scale Factor

Refer to "6.23: Incorrect Scaling Of Motor Current Sense" for the procedure to troubleshoot this problem.

7.12.5: Traction Motor Problem

Review the individual traction motor currents measured in "8.20: Motor Current Sense".

One of the traction motor currents was significantly lower than all the others,

Or:

One of the traction motor currents was significantly higher than all the others.

In either event this signifies an electrical problem with one of the traction motors or a slipping pinion. Complete the investigation with reference to the normal procedures for checking out traction motors.

7.13: Code 13-High Motor Current Sense

7.13.1: Introduction

This diagnostic code indicates that the derate module is not receiving a finite high motor current sense signal under conditions it would normally be expected to be receiving it.

7.13.2: Probable Cause

* Incorrect motor current sense scale factor.

* Wiring problem in main electronic governing system mounting group.

* Internal defect in derate module.

7.13.3: Check Scale Factor

Refer to "8.20: Motor Current Sense" for the procedure to measure the scale factor.

If the scale factor is correct proceed to "7.13.5: Check Mounting Group Wiring".

If the scale factor is not correct proceed to "7.13.4: Troubleshoot Wrong Scale Factor".

7.13.4: Troubleshoot Wrong Scale Factor

Refer to "6.23: Incorrect Scaling Of Motor Current Sense" for the procedure to troubleshoot this problem.

7.13.5: Check Mounting Group Wiring

1. Disconnect all battery power to TB391 and TB392.

2. Unplug the J1 connector from the main electronic governor box.

3. Check continuity between:

Derate Module Terminal 9-TB392-R4

Derate Module Terminal 6-TB391-L9

Also check for short circuits to battery positive (+), battery negative (-) and the locomotive chassis on the above connections. Make any necessary repairs.

4. If no repairs were necessary replace the derate module according to "8.4: Altitude Derate Module or Non-Altitude Derate Module".