GASKET HEAD 7C8956 - Caterpillar

MID 87 - Chassis ECMCID 144 - Backup Alarm RelayFMI 3 - Voltage Above Normal
Illustration 1 g01689526
"Backup Alarm" relay
Illustration 2 g01953397
"Backup Alarm" relay circuit
Note: The approximate coil resistance of the relay is 360 ohms at 25 °C (77.0 °F).This diagnostic code indicates the "Chassis ECM" detects "Backup Alarm" relay voltage that is above normal.This code can be caused by:
Failed relay
Shorted circuit
Failed ECMNote: The following test procedure may create other diagnostic codes. Ignore these created codes and clear these created codes after the original diagnostic code has been corrected. Ensure diagnostic code CID 144 FMI 3 is active before performing this procedure.Note: Use a calibrated digital multimeter for this procedure.System Response:The backup alarm is in the on position.Test Step 1. CHECK FOR A SHORT
Turn off the key switch and the disconnect switch.
Disconnect the harness from the relay and the "Chassis ECM".
At the harness connector for the ECM, measure the resistance from contact J2-13 (wire 321-BR(Brown)) to all contacts used in the harness connectors for the ECM.Expected Result:Each resistance is greater than 5000 ohms.Results:
OK - Each resistance is greater than 5000 ohms. Proceed to Test Step 3.
NOT OK - A resistance is less than 5000 ohms. There is a short between J2-13 (wire 321-BR(Brown)) and the circuit with low resistance.Repair: Repair or replace the harness.STOPTest Step 2. CHECK THE ECM OPERATIONThe disconnect switch and the key switch remain in the off position.The harness connectors for the solenoid and the ECM remain disconnected.
At the J2 connector for the "Chassis ECM", use a wire removal tool to remove wire 321-BR(Brown)from contact J2-13.
Reconnect the J1 and J2 harness connectors to the "Chassis ECM".
Turn on the disconnect switch and the key switch.
Observe the status of the active diagnostic code.Expected Result:CID 144 FMI 3 changes to CID 144 FMI 5.Results:
OK - CID 144 FMI 3 changes to CID 144 FMI 5 after the wire is disconnected. The ECM has responded correctly. Reinstall the disconnected wire to the correct space in the ECM connector. Proceed to Test Step 3.
NOT OK - CID 144 FMI 3 does not change to CID 144 FMI 5 when the wire was disconnected from the ECM. The ECM may have failed.Repair: Exit this procedure and perform this procedure again. Contact the technical communicator at your Caterpillar dealer. If the ECM requires replacement, see Testing and Adjusting, "Electronic Control Module (ECM) - Replace".STOPTest Step 3. CHECK THE DIAGNOSTIC CODE
Turn off the key switch and the disconnect switch.
Inspect the harness.Clean and inspect the harness connector contacts for corrosion or damage.Check the wire insulation for damage caused by heat, corrosion, or chafing.
Perform a 45 N (10 lb) pull test on each circuit wire.
Reconnect all harness connectors.Verify that the connectors are fully seated and the clips are fastened.
Check for intermittent problems. Use Cat® Electronic Technician (Cat® ET) to perform a wiggle test on the harness.
Turn on the disconnect switch and the key switch.
Operate the machine.
Determine if CID 144 FMI 3 is active.Expected Result:CID 144 FMI 3 is not active.Results:
OK - CID 144 FMI 3 is not active.Repair: