Use this procedure under the following situation:
Use the following information in order to determine if the warning lamp is operating incorrectly:
The following background information is related to the following procedure:
Warning Lamp Operation
A warning lamp is required if the "Engine Monitoring" feature is used. The warning lamp indicates an active problem with one of the monitored conditions such as high coolant temperature. A flashing warning lamp indicates that the engine is derating power. The warning lamp will turn on for a minimum of two seconds after the engine has started.
An option is available for the "GM Truck Manufacturer" configuration that allows the output for warning lamp to be configured as an output for a warning lamp for high coolant temperature. The "Engine Monitoring Lamps" parameter must be programmed to the "Warning Lamp" option for standard operation of engine monitoring. If the "Engine Monitoring Lamps" parameter is programmed to the "HIgh Coolant Temp Warning Lamp" option, the output is used as an interface to the GM shutdown system.
Operation Of Engine Monitoring
When the ECM has detected an engine condition that exceeds the acceptable limits, the warning lamp will turn on. The activation of the lamp depends on the existing conditions and the programming of the parameter for "Engine Monitoring". The lamp will activate in one of the following modes:
- The lamp not only turns on, but the lamp stays on.
- The lamp will flash on and off.
If the lamp turns on continuously, the engine is in warning mode. If the lamp begins to flash, the ECM has begun to derate engine speed, vehicle speed, or power.
If the parameter for Engine Monitoring is programmed to "WARNING", the lamp will not flash. The lamp only flashes when the engine is programmed to "DERATE" or "SHUTDOWN".
If the Customer Parameter for Engine Monitoring is programmed to "WARNING", "DERATE", or "SHUTDOWN" the lamp will turn on when a warning condition exists. The lamp will be turned on continuously while a warning condition exists.
If the Customer Parameter for Engine Monitoring is programmed to "DERATE" or "SHUTDOWN", the lamp flashes whenever Engine Monitoring is derating engine speed, vehicle speed, and power.
If the Customer Parameter for Engine Monitoring is programmed to "SHUTDOWN", the warning lamp will continue flashing after the derate mode until the engine is shut down. Refer to Troubleshooting, "System Overview".
Electrical Connection of Lamps
One terminal of the lamp must be connected to battery voltage through the vehicle wiring. The other terminal is connected to the ECM at the ECM vehicle harness connector J1/P1:29 (warning lamp).
The ECM provides a path to ground in order to turn the lamp ON.
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| Illustration 1 | g00769338 |
Circuit schematic for the warning lamp | |
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| Illustration 2 | g00769348 |
Pin locations for the warning lamp circuit | |
Test Step 1. Inspect Electrical Connectors and Wiring
- Thoroughly inspect ECM vehicle harness connector J1/P1, the firewall bulkhead connector, and terminal 29. Refer to Illustration 2. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
- Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that is associated with the suspect terminal for the lamp.
- Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).
- Check the harness and wiring for abrasion and pinch points from the battery to the ECM.
Expected Result:
All connectors, pins and sockets should be completely coupled and/or inserted and the harness and wiring should be free of corrosion, abrasion or pinch points.
Results:
- OK - Proceed to Test Step 2.
- Not OK -
Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.
STOP
Test Step 2. Check for Normal Operation of the Warning Lamp
- Monitor the warning lamp. Turn the ignition key switch to the ON position, while the engine is off. The lamp should turn on for five seconds. Then, the lamp should turn off.
The lamp will continue flashing if there is an active diagnostic code. If there is an active diagnostic code, connect Caterpillar Electronic Technician (Cat ET) in order to read the active diagnostic code. Troubleshoot the problem.
Note: The warning lamp will not turn on until the engine is cranked.
- Connect Cat ET to the cab data link connector. Verify that the "Engine Monitoring" has been programmed to "WARNING", "DERATE", or "SHUTDOWN".
While the warning lamp is being observed, start the engine. The warning lamp should turn on for a minimum of two seconds after the engine starts. Then, the warning lamp should turn off. If the lamp remains off, immediately shut down the engine.
Expected Result:
The warning lamp turns on and the warning lamp turns off per the above description.
Results:
- OK - The lamp appears to operating correctly at this time.STOP
- Not OK - The lamp does not turn on. Proceed to Test Step 3.
- Not OK - The lamp stays on.
Repair: Perform the following diagnostic procedure:Use Cat ET to determine if an "Engine Monitoring" condition is causing the lamp to turn on. If an "Engine Monitoring" condition is not present, perform the following diagnostic procedure.
Proceed to Test Step 3.
Test Step 3. Test the Lamp Circuit
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| Illustration 3 | g00769361 |
Vehicle harness connector P1 | |
- Disconnect ECM vehicle harness connector J1/P1.
- Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.
- Insert the jumper intoP1:29 (warning lamp). The jumper can be inserted into the following terminals in order to test the appropriate lamp circuit:
- Connect the other side of the jumper wire to P1:65 (-battery).
- Turn the ignition key switch to the ON position.
- While the lamp is being watched, insert the jumper wire and remove the jumper wire.
Refer to Illustration 3.
Expected Result:
Result 1 The warning lamp turns on while the jumper is connected to both sockets. Also, the warning lamp turns off when the jumper is removed from one of the sockets.
Result 2 The lamp does not turn on while the jumper is connected to both sockets.
Result 3 The lamp will stay on while the ECM vehicle harness connector is disconnected.
Results:
- Result 1 - The warning lamp circuit is functioning properly. Proceed to Test Step 4.
- Result 2 - The lamp did not turn on. The vehicle's lamp circuit is not functioning properly. The lamp is probably burned out or there is a problem in the wiring from the cab to either the ECM or the +battery connection. Repair the lamp circuit or send the vehicle to the OEM dealer for repairs.STOP
- Result 3 -
Repair: Perform the following diagnostic procedure:The circuit between the ECM and the lamp is shorted to chassis ground. Repair the circuit or send the vehicle to the OEM dealer for repairs.
STOP
Test Step 4. Check the Operation of the ECM Output for the Warning Lamp
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| Illustration 4 | g00769368 |
ECM breakout T-connector | |
- Disconnect ECM vehicle harness connector J1/P1.
- Insert a breakout T between the ECM vehicle harness connectors J1 and P1.
- Connect a test light probe to terminal 65 (-battery) and connect the other probe to terminal 52 (unswitched +battery) of the breakout T.
- The test lamp should turn on. If the test lamp does not turn on, either the test lamp is faulty or the wiring to the ECM is faulty. Continue with this step if the lamp turns on.
- Leave the test light probe connected to terminal 52 (unswitched +battery).
- Connect the other test light probe to terminal 29 on the breakout T.
Refer to Illustration 4.
- Watch the voltage test lamp. Start the engine. The lamp should turn on for a minimum of two seconds after the engine starts. Then, the lamp should turn off. Immediately turn the engine off if the lamp continues to stay on. Use Cat ET to determine the cause of the problem.
Expected Result:
The warning lamp turns on and the warning lamp turns off per the above description.
Results:
- Yes - The ECM is operating correctly. There is a problem in the vehicle wiring or the lamp. Repair the vehicle wiring or the lamp, as required.STOP
- No - Temporarily connect a test ECM. Ensure that the "Engine Monitoring" parameter of the test ECM matches the "Engine Monitoring" parameter of the suspect ECM. Check the operation of the ECM output for the lamp when the test ECM is installed. If the problem is resolved with the test ECM, reconnect the suspect ECM. If the problem returns with the suspect ECM, replace the ECM.STOP