TUBE AS 3V3268 - Caterpillar

The diagnostic circuit of the Power Train ECM identifies a system voltage that is below 21.3 DCV.The possible causes of this diagnostic code are listed:
The system voltage remains low for an extended time after the engine is started.
There is a connection with high impedance between the battery and the ECM.
There is a connection with high impedance between the ECM and system ground.
One set of batteries is disconnected with the key in the ON position. Also, the engine must not be running.Note: Ensure that the diagnostic code is active and that the diagnostic code indicator is active.Test Step 1. CHECK THE BATTERY VOLTAGE
Start the engine and operate the engine at high idle for several minutes. Expected Result:Battery voltage is greater than 21.3 DCV.Results:
YES - Battery voltage is greater than 21.3 DCV. The battery voltage is correct. Proceed to Test Step 2.
NO - Battery voltage is below 21.3 DCV.Repair: The charging system is not operating correctly. Check the charging system. Refer to Special Instruction, REHS0354, "Charging System Troubleshooting".STOPTest Step 2. CHECK THE SYSTEM VOLTAGE AT THE POWER TRAIN ECM
The engine must be running at high idle.
Measure the system voltage between contact J1-1 (wire 164-WH(White)) and contacts J1-13, J1-23, J1-57 and J1-70 (wire 202-BK(Black)). Measure the system voltage at the contacts of the harness connector. Expected Result:The voltage is below 21.3 DCV.Results:
YES - Voltage is below 21.3 DCV.Repair: Repair the harness or replace the harness.STOP
NO - Voltage is greater than 21.3 DCV.Repair: The system voltage is correct. Ensure that service code CID 0168 FMI 01 is still active. Disconnect the Power Train ECM. Inspect contacts J1-1 and J1-13, J1-23, J1-57 and J1-70 (wire 202-BK(Black)). Connect the harness connector to the Power Train ECM. If the diagnostic code is active, replace the Power Train ECM. Refer to Systems Operation, Troubleshooting, Testing and Adjusting, "Electronic Control Module (Power Train) - Replace" for the machine that is being serviced.STOP