PIPE AS 3157261 - Caterpillar

Illustration 1 g02548997
Schematic of Back Up Alarm RelayThis diagnostic code is associated with the Back Up Alarm Relay. The backup alarm relay is controlled by the ECM through an ON/OFF output driver. The FMI 03 means that the ECM has determined that the voltage is present in the relay circuit when the output driver is OFF.The conditions that could cause this diagnostic code to activate are listed:
The relay has failed.
The energize circuit of the relay is shorted to another voltage source.
The ECM has failed. The failure of the ECM is unlikely.Note: Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit meet the following requirements: clean, secure and good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure. Note: The following test procedure may cause other diagnostic codes to be activated. Ignore these created diagnostic codes and clear the diagnostic codes when the problem has been corrected.Note: Use a calibrated digital multimeter for the measurements in this procedure.System Response:The backup alarm is on.Test Step 1. CHECK THE RELAY
Turn the key start switch and the disconnect switch to the ON position.
While the status of the active CID 0144 FMI 03 diagnostic code is being observed, disconnect the backup alarm relay from the machine harness.
At the relay, measure the resistance of the coil between contact 85 and contact 86. Measure the resistance between power contact 30 and all