STAIRWAY GP 3532779 - Caterpillar

Which Generate This Code:This diagnostic code is recorded when the system voltage is below 9 VDC. The brakes will be applied and the transmission will shift into neutral.The possible causes of this diagnostic code are listed below:
The wiring in the machine harness has failed.
A charging system component has failed.
Low system voltage events.
The ECM may have failed. The failure of an ECM 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. Test Step 1. CHECK THE BATTERY VOLTAGE.
Start the engine and run at high idle for several minutes.
Measure the battery voltage at the battery posts. Expected Result:Battery voltage should be greater than 9 VDC. Results:
OK - Battery voltage is greater than 9 VDC. Battery voltage is correct. Proceed to Test Step 2.
NOT OK - Battery voltage is not greater than 9 VDC.Repair: The charging system is not correct. Check the charging system. See Diagnostic System Procedures, "Charging System".STOPTest Step 2. CHECK THE SYSTEM VOLTAGE AT THE ECM.
The engine must still be running at high idle.
DO NOT DISCONNECT the machine harness from the ECM. At connector "J1" of the ECM, prepare to make a voltage measurement by using the 7X-1710 Multimeter Probe.
At the machine harness for the ECM, insert the probe into the back of connector "J1". Measure the voltage (VDC) between J1-39 (wire 126-RD) and J1-23 (wire 202-BK). Expected Result:Voltage should be greater than 9 VDC. Results:
OK - Voltage is greater than 9 VDC. Battery voltage is correct. Proceed to Test Step 3.
NOT OK - Voltage is not greater than 9 VDC.Repair: The machine harness is not correct. Repair the machine harness or replace the machine harness.STOPTest Step 3. CHECK IF THE DIAGNOSTIC CODE IS STILL ACTIVE.
Remove connectors "J1" and "J2" from the ECM. Inspect the contacts and clean the contacts of the harness connectors.
Reconnect all harness connectors.
Turn the key start switch to the ON position.
Operate the machine.
Determine if CID 0168 FMI 04 is present. Expected Result:CID 0168 FMI 04 is present. Results:
YES - CID 0168 FMI 04 is present. Repair: Exit this procedure and perform the diagnostic code procedure again. If the problem persists, the ECM may have failed. Prior to replacing an ECM, always contact your Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".STOP
NO - CID 0168 FMI 04 is not present.Repair: The diagnostic code is NOT present. The problem does not exist at this time. The initial problem was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.STOP