SEAL 3T7135 - Caterpillar

Illustration 1 g01250741
Schematic of the Backup Alarm RelayThis diagnostic trouble code is associated with the backup alarm relay. The FMI 06 means that the ECU has determined that there is a short to ground in the relay circuit. The possible causes of this diagnostic trouble code are listed:
The energize circuit of the relay is shorted to ground.
The relay has failed.
The ECU has failed. This is unlikely. Note: The following test procedure may create other diagnostic trouble codes. Ignore these created diagnostic trouble codes and clear these diagnostic trouble codes when the original diagnostic trouble code has been corrected. Ensure that the diagnostic trouble code of CID 0144 FMI 06 is active before performing this procedure.Note: Use a 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 trouble code.
Disconnect the relay with the active diagnostic trouble code from the machine harness. Expected Result:CID 0144 FMI 06 changes to CID 0144 FMI 05 when the relay is disconnected.Results:
YES - CID 0144 FMI 06 changes to CID 0144 FMI 05 when the relay is disconnected. The circuit is correct.Repair: The relay has failed. Replace the relay. Verify that the new relay corrects the problem.STOP
NO - CID 0144 FMI 06 remains active. Proceed to Test Step 2.Test Step 2. CHECK THE ENERGIZE 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 ECU.
At the machine harness connector, measure the resistance from the signal contact J2-5 (wire 331-OR) to all contacts that are used in the machine harness connectors for the ECU. 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 J2-5 (wire 331-OR) 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 TROUBLE CODE REMAINS.
Inspect the harness connectors and clean the contacts of the harness connectors and check the wires for damage to the insulation that is caused by excessive heat, battery acid, or chafing.
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit.
Reconnect all harness connectors making sure that the connectors are fully seated and the clips for each connector are completely fastened.
Turn the disconnect switch and the key start switch to the ON position.
Operate the machine.
Check the status of the CID 0144 FMI 06. Expected Result:The CID 0144 FMI 06 is active. Results:
YES - The CID 0144 FMI 06 is active. The diagnostic trouble code has not been corrected.Repair: Check the relay circuit again.