PLATE 8H8548 - Caterpillar

Which Generate This Code:This diagnostic code is recorded when the system voltage is greater than 16.0 DCV. The solenoids may be damaged if the voltage remains high for an extended period of time. The possible causes of this diagnostic code are listed below:
A charging system component has failed.
The harness wiring has failed.
The ECM has failed. This is unlikely. Test Step 1. CHECK THE CHARGING SYSTEM.
Turn the key start switch to the ON position.
Observe the status of the diagnostic code.Expected Result:The diagnostic code is active. See Special Instruction, SEHS0354, "Charging System Troubleshooting".Results:
YES - The diagnostic code is active. Proceed to Test Step 3.
NO - The diagnostic code is NOT active. Proceed to Test Step 2.Test Step 2. CHECK THE CHARGING SYSTEM.
Start the engine.
Observe the status of the diagnostic code.Expected Result:The diagnostic code is active. See Special Instruction, SEHS0354, "Charging System Troubleshooting".Results:
YES - The diagnostic code is active.Repair: The charging system is charging at an excessive voltage. Check the charging system. Proceed to Test Step 3.
NO - The diagnostic code is not active. Repair: There is no problem at this time. Watch for a recurrence.STOPTest Step 3. CHECK THE BATTERY VOLTAGE.
The engine is stopped. At the battery, measure the voltage. Expected Result:The voltage is less than 16.0 VDC.Results:
YES - The voltage is less than 16.0 VDC.Repair: Exit this procedure and perform the diagnostic code procedure again. If the problem persists, the ECM may have failed. Prior to replacing the ECM, contact your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. See Troubleshooting, "Electronic Control Module (ECM) - Replace" for more information.STOP
NO - The voltage is not less than 16.0 VDC.Repair: The charging system is charging at an excessive voltage. Check the charging system. See Special Instruction, SEHS0354, "Charging System Troubleshooting".STOP