HOOD & GUARD GP 3975422 - Caterpillar

Illustration 1 g02160296
Schematic for Machine ECM Electrical System VoltageThis diagnostic code is recorded when the Machine ECM reads the system voltage as being below 18 DCV.Note: The Machine ECM is located inside the Center Console.The possible causes of this diagnostic code are listed:
A charging system component has failed.
The machine harness has failed.
The ECM has failed. This situation is unlikely. System Response:Components connected to the controller will not log faults. Machine may become inoperable.Test Step 1. CHECK THE BATTERY VOLTAGE.
Start the engine and run the engine at high idle for several minutes.
Measure the voltage of the battery at the battery posts.Expected Result:The battery voltage should be greater than 18 DCV.Results:
OK - The battery voltage is greater than 18 DCV. The battery voltage is correct. Proceed to test step 2.
NOT OK - The battery voltage is NOT greater than 18 DCV.Repair: Check the charging system. See Special Instruction, REHS0354.STOPTest Step 2. CHECK THE SYSTEM VOLTAGE AT THE ECM.
The engine remains running at high idle.
DO NOT DISCONNECT the machine harness from the ECM.
Use the 7x-1710 Multimeter Probe to measure the positive voltage (DCV) between contacts J1-31, J1-39, J1-47 (wire 149-PU) and ground contacts J1-13, J1-23, J1-26, J1-32, J1-57 (wire 200-BK). Expected Result:The voltage measurement is greater than 18 DCV.Results:
OK - The voltage is greater than 18 DCV. The battery voltage is correct. Proceed to test step 3.
NOT OK - The voltage is NOT correct. The machine harness has failed.Repair: Repair the machine harness or replace the machine harness.STOPTest Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connectors from the ECM. Inspect the harness and clean the contacts of the harness connectors.
Reconnect all harness connectors.
Turn the disconnect switch and the key start switch to the ON position.
Clear all the active diagnostic codes.
Operate the machine.
View the status of CID 0168 FMI 04.Expected Result:The diagnostic code is NO longer active.Results:
YES - The diagnostic code is NO longer active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor electrical connection. The disconnection and reconnection of the harness connectors may have solved the problem. Resume normal machine operation.STOP
NO - The diagnostic code has NOT been corrected. The ECM may have failed.Repair: Prior to replacing an ECM, always contact Technical Communicator for 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