HEAD 3G8186 - Caterpillar

Illustration 1 g01453510
Connections of the backup alarm
This diagnostic code is associated with the backup alarm. The FMI 03 means that the ECM has determined that the voltage of the alarm circuit is above normal. The possible causes of the diagnostic code are listed:
The alarm has failed.
The energize circuit of the alarm is shorted to the +battery circuit.
The ECM has failed. This is unlikely.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 of the connections in the circuit are clean and secure. 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 create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the problem has been corrected. Verify that the CID 0637 FMI 03 is active before performing this procedure.Use a digital multimeter for the measurements in this procedure.Test Step 1. CHECK THE ENERGIZE CIRCUIT OF THE ALARM FOR A SHORT TO THE +BATTERY CIRCUIT.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connectors from the alarm and the ECM.
At the machine harness connector for the ECM, measure the resistance from contact J1-12 (wire F916-GN(Green)) to all contacts that are used in the machine harness connectors for the ECM. Expected Result:Each resistance measurement is greater than 5000 ohms. Results:
OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 2.
NOT OK - Each resistance measurement is not greater than 5000 ohms. There is a short in the machine harness. The short is between J1-12 (F916-GN(Green)) and the circuit that has a low resistance measurement. Repair: Repair the machine harness or replace the machine harness.STOPTest Step 2. CHECK IF THE DIAGNOSTIC CODE IS STILL ACTIVE.
Inspect the harness connectors. Clean the contacts of the harness connectors and check the wires for damage to the insulation that is caused by excessive heat, battery acid, or chafing.
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit.
Reconnect all harness connectors in order to make sure that the connectors are fully seated. Also, make sure that the clips for each connector are completely fastened.
Turn the disconnect switch and the key start switch to the ON position.
Operate the machine.
Check the status of the diagnostic code. Expected Result:The diagnostic code is active.Results:
YES - The diagnostic code is active. The diagnostic code has not been corrected.Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. Prior to replacing an ECM, always contact your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Troubleshooting, "Electronic Control Module (ECM) - Replace".STOP
NO - The diagnostic code is not active. The initial diagnostic code was probably