HEAD 1149323 - Caterpillar

Illustration 1 g02040914
Schematic of the backup alarm circuitThis diagnostic code is recorded when the Computerized Profiler Control ECM detects an below normal current of the circuit for the backup alarm.The possible causes of this diagnostic code are listed below:
The energizer circuit of the backup alarm is open.
The return circuit of the backup alarm is open.
The backup alarm is faulty.
The ECM has failed. This is unlikely.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear these diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 0391 FMI 05 is active before performing this procedure.Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.Test Step 1. CHECK THE BACKUP ALARM
Turn the key start switch to the ON position.Note: Do not start the engine. Ensure that the diagnostic code CID 637 FMI F05 is active.
Disconnect the machine harness from the backup alarm and the ECM.
At the machine harness connector or terminals for the backup alarm, place a jumper from the signal wire to the return contact (wire 229-BK).
Observe the status of the CID 637 FMI F05.Expected Result:The CID 637 FMI 05 remains active. The FMI has not changed and the 05 is still active.Results:
OK - The diagnostic code remains active. The jumper wire does not affect the diagnostic code. Proceed to Test Step 2.
NOT OK - The diagnostic code is no longer active. The backup alarm has failed.Repair: Repeat the test "CHECK THE BACKUP ALARM" in order to verify the failure of the backup alarm. Replace the backup alarm.STOPTest Step 2. CHECK THE HARNESS CIRCUITS FOR AN OPEN
Turn the key start switch to the OFF position.
Disconnect the machine harness connector from the ECM.
The jumper wire that was installed in the previous Test Step remains in place.
At the ECM machine harness connector, measure the resistance from the energizer circuit or signal contact to the return wire (229-BK).Expected Result:There should be continuity (less than 5.0 ohms resistance).Results:
OK - There is continuity (less than 5.0 ohms resistance). The machine harness is correct. Proceed to Test Step 3.
NOT OK - There is an open circuit in the machine harness. The open is in the wire for the energizer circuit or in wire (229-BK) of the machine harness.Repair: Repair the machine harness or replace the machine harness.STOPTest Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS
Inspect and clean the contacts of the harness connectors.
Reconnect all harness connectors.
Turn the key start switch to the ON position.
Enter diagnostic mode of the Computerized Profiler Control ECM and clear all inactive diagnostic codes.
Operate the machine.
Check the status of the CID 637 FMI F05.Expected Result:The CID 637 FMI F05 is active.Results:
OK - The CID 637 FMI F05 is active. The diagnostic code has not been corrected. The ECM may have failed.Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. Refer to the Electrical Schematic of the machine and check all involved wiring harness connectors and wiring. Ensure that