GUARD AS 1692187 - Caterpillar

Illustration 1 g01099209
Schematic of the relay (brake light)
This diagnostic code is associated with the relay (brake light). The FMI 05 means that the ECM has determined that the current of the relay is below normal. The possible causes of this diagnostic code are listed below:
The signal circuit of the relay is open.
The return circuit of the relay is open.
The relay has failed.
The ECM has failed. This is unlikely. Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear these diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 0742 FMI 05 is active before performing this procedure.Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.Test Step 1. CHECK THE RELAY.
Turn the disconnect switch and the key start switch to the ON position. Do not start the engine.
Disconnect the relay with the active diagnostic code from the machine harness.
At the machine harness connector for the relay, place a jumper wire from contact 86 (wire 958-YL(Yellow)) to contact 85 (wire K927-BU(Blue)).
Observe the status of the CID 0742 FMI 05. Expected Result:The CID 0742 FMI 05 remains active. The FMI has not changed and the "05" is still active.Results:
YES - The diagnostic code remains active. The jumper wire does not affect the diagnostic code. Proceed to Test Step 2.
NO - The diagnostic is no longer active. The relay has failed.Repair: The relay has failed. Repeat this Test Step "CHECK THE RELAY" in order to verify the failure of the relay. Replace the relay. Verify that the new relay corrects the problem.STOPTest Step 2. CHECK THE HARNESS FOR AN OPEN.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connector(s) from the ECM.
The jumper wire that was installed in the previous test remains in place.
At the machine harness connector, measure the resistance from signal contact J2-37 (wire 958-YL(Yellow)) to contact J2-3 (wire K927-BU(Blue)). Expected Result:The resistance is less than 5.0 ohms.Results:
OK - The resistance is less than 5.0 ohms. The machine harness is correct. Proceed to Test Step 3.
NOT OK - The resistance is greater than 5000 ohms. The resistance measurement is not correct. There is an open circuit in the machine harness.Repair: The open is in wire 958-YL(Yellow) or in wire K927-BU(Blue) of the machine harness. Repair the machine harness or replace the machine harness.STOPTest Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS.
Inspect the contacts of the harness connectors and clean the harness connectors.
Reconnect all harness connectors.
Turn the disconnect switch and the key start switch to the ON position.
Operate the machine.
Check the status of the CID 0742 FMI 05. Expected Result:The CID 0742 FMI 05 is active. Results:
YES - The CID 0742 FMI 05 is active. The diagnostic code has not been corrected. The ECM may have failed.Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECM.