PARTS GP-MISCELLANEOUS 3151551 - Caterpillar

Illustration 1 g02276325
Schematic of the System Voltage.
This diagnostic code is recorded when the Messenger module reads the electrical system voltage at Contact 1 at an above-normal range (more than 29.5 V for two seconds).The possible causes of this diagnostic code are listed below:
A charging system component has failed.
The Messenger module may have failed. This cause is unlikely.Note: Check the 15 amp fuse to make sure that the fuse is not disengaged.Test Step 1. CHECK FOR AN ACTIVE DIAGNOSTIC CODE
Turn the disconnect switch and the key start switch to the ON position.
View the status of the diagnostic code. Expected Result:The diagnostic code is NOT active.Results:
YES - The diagnostic code is NOT active.Repair: The diagnostic code is NOT active. The problem does not exist at this time. Watch for a recurrence.STOP
NO - The diagnostic code is active. Proceed to Test Step 2.Test Step 2. CHECK THE CHARGING SYSTEM
Start the engine.
Run the engine at high idle.
View the status of the diagnostic code. Expected Result:The diagnostic code is NOT active.Results:
YES - The diagnostic code is NOT active. Watch for a recurrence.STOP
NO - The diagnostic code is active.Repair: The charging system is charging at an excessive voltage. Check the charging system. See Special Instruction, REHS0354, "Charging System Troubleshooting".STOP