MOUNT-ENGINE 1745516 - Caterpillar

Illustration 1 g01113771Backup AlarmThis diagnostic code is recorded when the ECM reads the voltage of the backup alarm circuit as above normal (short to +V).The possible causes of this diagnostic code are:
The energize signal circuit for the backup alarm is shorted to +V.
The ECM has failed. This is unlikely.System Response:The results of this diagnostic code are:
Propel diagnostic code lamp on the machine operator's station will be ON.
The backup alarm will always be ON.Note: Ensure that the diagnostic code CID 042 FMI F03 for the backup alarm is on hold and that the diagnostic code present indicator on the ECM display is ON.Test Step 1. Check Backup Alarm Energize Circuit For Short To +V
Turn the key start switch to the OFF position.
Disconnect the machine harness from the backup alarm.
Disconnect the machine harness connector from the ECM.
At the machine harness connector, measure the resistance from the energize signal circuit at ECM contact 36 (wire P304-WH(White)) to all other possible sources of +V. The possible sources of positive voltage are ECM contacts 1, 10, 11, 31, 32, 33, 34, 35, 36, 37, 38, and 40. Expected Result:Each resistance should be greater than 5000 ohms.Results:
OK - Each resistance measurement is greater than 5000 ohms. Proceed to Test Step 2.
NOT OK - One or more resistance measurements is less than 5000 ohms.Repair: There is a short in the machine harness. The short is between the energize signal circuit at ECM contact 36 (wire P304-WH(White)) and the circuit with the low resistance measurement. Repair or replace the machine harness.STOPTest Step 2. Check To See If Diagnostic Code Remains
Clean the contacts of the harness connectors.
Reconnect all harness connectors.
Turn the key start switch to the ON position.
Enter service mode 1 on the ECM three digit display. Clear all inactive diagnostic codes.
Operate the machine.
Check to see if the CID 042 FMI F03 diagnostic code for the backup alarm is present (diagnostic code present indicator ON). Expected Result:The CID 042 FMI F03 diagnostic code for the backup alarm is not present.Results:
OK - The CID 042 FMI F03 diagnostic code for the backup alarm is not present. The machine harness and the ECM are operating properly.Repair: The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.STOP
NOT OK - The CID 042 FMI F03 diagnostic code for the backup alarm is still present.Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. Refer to the Electrical System Schematic for this machine and check all involved wiring harness connectors and wiring. Ensure that the connector contacts are clean and in good condition. Ensure that all machine harness wiring is intact and in good condition. If the cause of this error code is not found, replace the ECM. See Testing and Adjusting, "Electronic Control Module (ECM) − Replace" in this manual.STOP