Use this procedure to troubleshoot the electrical system if a problem is suspected with the indicator lights or if another procedure has sent you here.
Use this procedure to troubleshoot any suspect problems with the following indicator lamps:
- Maintenance indicator lamp
- Warning lamp
- Diagnostic lamp
The indicator lamps are activated by the Electronic Control Module (ECM) in order to inform the operator of various engine conditions. When the keyswitch is placed in the ON position, the diagnostic lamp and the warning lamp is illuminated by the ECM for a brief period.
The ECM provides a high side driver for all of the lamp outputs. The most likely cause of a problem with an indicator lamp is the bulb. The next most likely cause is a problem with a wire or with a connector. The least cause is a problem with the ECM.
Note: An override feature is available in Caterpillar Electronic Technician (ET) for each of the lamp circuits. The override can be used to troubleshoot the lamp circuits.
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| Illustration 1 | g01382261 |
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Schematic for the engine's lamp circuits | |
Note: There is a configuration parameter that is associated with the maintenance indicator lamp. Ensure that these parameters are configured correctly prior to troubleshooting the lamp circuits. Refer to Troubleshooting, "Configuration Parameters" for information that is related to the configuration of the lamp circuits.
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The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere. |
Test Step 1. Inspect the Electrical Connectors and the Wiring
- Remove electrical power from the ECM.
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Illustration 2 g01367265 Locations of the connectors that are associated with the lamp circuits (typical left rear engine view)
(1) Engine interface connectors
(2) J2/P2 ECM connectors
(3) J1/P1 ECM connectors - Thoroughly inspect connectors (1), (2), and (3). Also, thoroughly inspect any of the other connectors that are associated with the lamp circuits. Refer to the Schematic of the engine for connector locations. Refer to Troubleshooting, "Electrical Connectors - Inspect".
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Illustration 3 g01382292 Terminal locations at the P1 ECM connector that are for the lamp circuits
(P1-28) Diagnostic lamp
(P1-29) Warning lamp
(P1-30) Maintenance indicator lampShow/hide table
Illustration 4 g01389061 Terminals at the customer connector that are associated with the lamp circuits
(13) Diagnostic lamp
(24) Warning lamp
(25) Maintenance indicator lamp - Perform a
45 N (10 lb) pull test on each of the wires for the lamp circuits. - Check the torque of the allen head screw on the ECM connectors and the engine interface connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
- Check the harness and the wiring for abrasion and for pinch points from the dash display back to the ECM.
Expected Result:
All of the connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion and of pinch points.
Results:
- OK - The harness and connectors appear to be in good repair. Proceed to Test Step 2.
- Not OK - The connectors and/or wiring need repair.
Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled. Verify that the repair eliminates the problem.
STOP
Test Step 2. Check for Proper Operation of the Lamp Circuits
- Connect Cat ET to the service tool connector.
- Restore electrical power to the ECM.
- Select the "Override Parameters" option from the "Diagnostic Tests"on Cat ET.
- Use the correct override parameter to power the circuit for the suspect lamp.
- Remove electrical power from the ECM.
Expected Result:
The suspect lamp illuminates when the override is turned on.
Results:
- OK - The suspect lamp illuminates when the override is on.
Repair: There does not appear to be a problem with the lamp circuit at this time. The problem may have been related to a faulty connection in the harness. Carefully reinspect the connectors and wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect".
STOP
- Not OK - The suspect lamp does not illuminate when the override is on. Inspect the lamp and the lamp socket for the suspect circuit. If either of the components are questionable, replace the component. Retest the circuit. If the problem persists or if the components of the lamp assembly appear to be in good repair, proceed to Test Step 3.
Test Step 3. Use the Override to Check the Wiring Harness
- Remove the lamp for the suspect circuit from the lamp socket.
- Connect a test lamp between the terminal that is for the driver circuit from the ECM and the −Battery terminal.
- Restore electrical power to the ECM.
- Use the override parameter in Cat ET to power the circuit for the suspect lamp.
- Remove electrical power from the ECM.
Expected Result:
The test lamp illuminates when the override is turned on.
Results:
- OK - The test lamp illuminates when the override is turned on.
Repair: Check for continuity between the negative terminal of the lamp socket and −Battery.
If the circuit is continuous then the lamp or the lamp socket is the cause of the problem. Replace the faulty lamp or the faulty lamp socket. Verify that the repair eliminates the original problem.
If the circuit is not continuous then there is a problem in the ground circuit for the lamp. Repair the ground circuit. Verify that the repair eliminates the original problem.
STOP
- Not OK - The test lamp does not illuminate when the override is turned on. There is a problem in the harness or in a connector. There may be a problem with the ECM. Proceed to Test Step 4.
Test Step 4. Check for Proper Operation of the ECM
- Ensure that electrical power has been removed from the ECM.
- Disconnect the appropriate ECM connectors for the suspect lamp circuit.
- Remove the signal wire for the suspect lamp from the ECM connector. Refer to Illustration 1 for the correct terminal locations.
- Fabricate a jumper wire that is long enough to create a test circuit between the ECM connector and the negative battery connection. Crimp a connector socket to one end of the jumper wire.
- Install the socket end of the jumper wire into the terminal location that is for the signal wire of the suspect lamp.
- Reconnect the ECM connectors.
- Connect a test lamp between the loose end of the jumper wire and −Battery.
- Restore electrical power to the ECM.
- Use the override parameter in Cat ET to power the circuit for the suspect lamp.
- Remove electrical power from the ECM. Restore all wiring to the original configuration.
Expected Result:
The test lamp illuminates when the override is turned on.
Results:
- OK - The test lamp illuminates when the override is on.
Repair: The ECM is operating correctly. There is a problem in the harness or in a connector. Repair the harness and/or the connector or replace the harness and/or the connector. If necessary, replace parts. Verify that the repair eliminates the problem.
STOP
- Not OK - The test lamp does not illuminate when the override is on.
Repair: The harness that is for the lamp circuit is OK. The ECM is not powering the lamp circuit correctly. Replace the ECM. Refer to Troubleshooting, "ECM - Replace" for details.
STOP