RELAY 8U7440 - Caterpillar

Illustration 1 g01365217
This diagnostic code is recorded when the LH Operator ECM reads the system voltage as being below 18 DCV.Note: (MAT, BPA, B5D, GNZ, TFZ, B6K machines) The LH Operator ECM is located under the LH Operator Platform.Note: (MAN, GNN, TFM machines) The Operator ECM is located inside the station console attached to the service door.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 is unlikely. System Response:When this diagnostic code is active, the following occurs:
Components connected to 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 (wire 151-RD) and ground contacts J1-13, J1-23 (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View the status of CID 0168 FMI 04.Expected Result:The diagnostic code is NO longer active.Results:
YES - The diagnostic code is NO longer active.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 or a short at one of the harness connectors that was disconnected and reconnected.STOP
NO - The diagnostic code has NOT been corrected. Repair: Resume normal machine operation. It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECM. See Troubleshooting, "Electronic Control Module (ECM) - Replace".STOP