PLATE AS-SIDE 4416463 - Caterpillar

Illustration 1 g00588671
Schematic for the Backup AlarmThe ECM applies power to the backup alarm whenever the ECM receives a signal from the reverse direction switch.Ensure that there are no active faults on the direction switch.Test Step 1. Check the backup alarmIf the backup alarm is always OFF the following items may occur:
The backup alarm is faulty.
The harness circuit is open.
The harness circuit is shorted to ground.
The ECM is faulty.
Disconnect the backup alarm from the machine harness.
Use jumpers to connect the respective terminals of the backup alarm to +battery and ground.Expected Result:The backup alarm sounds when power is applied.Results:
YES - The backup alarm operates correctly. Proceed to Test Step 2.
NO - The backup alarm does NOT sound. The backup alarm is faulty.Repair: Replace the backup alarm. Stop.Test Step 2. Check for a shorted harnessThe backup alarm remains disconnected.
Turn the disconnect switch to the OFF position.
Disconnect the ECM from the machine harness.
At the machine harness connector for the ECM, measure the resistance between contact J2-37 (wire 321-BR) and contact J1-7 (ground) or contact J2-3 (ground).Expected Result:Each resistance should be greater than 5000 ohms.Results:
YES - The resistance is greater than 5000 Ohms (no continuity). The resistance of the harness circuit is correct. Proceed to Test Step 3.
NO - The resistance is less than 5000 Ohms (continuity). The machine harness is faulty. Wire 321-BR is shorted to ground in the machine harness.Repair: Repair the machine harness or replace the machine harness. Stop.Test Step 3. Check for an open in the harness.The backup alarm and the ECM remain disconnected from the machine harness.
The disconnect switch remains OFF.
At the machine harness connector for the ECM, place a jumper from contact J2-37 (wire 321-BR) to contact J2-3 (wire 975-WH).
At the machine harness for the backup alarm, measure the resistance between wire 975-WH and wire 321-BR.Expected Result:There should be continuity.Results:
YES - The resistance is less than 5000 Ohms (continuity). The harness circuit resistance is correct. It is unlikely that the ECM is faulty. Perform these Steps again.Repair: If the cause is not found, replace the ECM. See Testing And Adjusting, "Electronic Control Module (ECM) - Replace". Stop.
NO - The resistance is greater than 5000 Ohms (no continuity). The harness circuit is faulty. Wire 975-WH or wire 321-BR is open in the machine harness between the ECM and the backup alarm.Repair: Repair the machine harness or replace the machine harness. Stop.