GUARD AS 1692190 - Caterpillar

Illustration 1 g01099319
Schematic of the relay (brake light)
This diagnostic code is associated with the relay (brake light). The FMI 06 means that the ECM has determined that the current of the relay is above normal. The possible causes of this diagnostic code are listed:
The signal circuit of the relay is shorted to ground.
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 06 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.
Observe the status of the diagnostic code.
Disconnect the relay with the active diagnostic code from the machine harness. Expected Result:CID 0742 FMI 06 changes to CID 0742 FMI 05 when the relay is disconnected.Results:
YES - CID 0742 FMI 06 changes to CID 0742 FMI 05 when the relay is disconnected. The circuit is correct.Repair: The relay has failed. Repeat this test "CHECK THE RELAY" in order to verify the failure of the relay. Replace the relay.STOP
NO - CID 0742 FMI 06 remains active. Proceed to Test Step 2.Test Step 2. CHECK THE SIGNAL CIRCUIT OF THE RELAY FOR A SHORT TO GROUND.
Turn the key start switch and the disconnect switch to the OFF position.
The relay remains disconnected from the machine harness.
Disconnect the machine harness connector(s) from the ECM.
At the machine harness connector, measure the resistance from the signal contact J2-37 (wire 958-YL(Yellow)) to all contacts that are used in the machine harness connectors for the ECM. Expected Result:Each resistance measurement is greater than 5000 ohms.Results:
OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 3.
NOT OK - Each resistance measurement is not greater than 5000 ohms. There is a short in the machine harness. The short is between J2-37 (wire 958-YL(Yellow)) and the circuit with the low resistance measurement.Repair: Repair the machine harness or replace the machine harness. STOPTest Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS.
Inspect the harness connectors and clean the contacts of 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 06. Expected Result:The CID 0742 FMI 06 is active. Results:
YES - The CID 0742 FMI 06 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. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace". STOP
NO - The CID 0742 FMI 06 is not active. The diagnostic code does not exist at this time.