SPIDER AS-FAN 1186840 - Caterpillar

Illustration 1 g02276325
Schematic of the System VoltageA CID 0168 is associated with the Messenger module. An FMI 04 means that the Messenger module found the electric system voltage input at contact 1 was below normal for over 2 seconds.Possible causes of this diagnostic code are:
A failed charging system component.
The wire harness has failed.
A failed Messenger module, but is unlikely.System Response:The outputs of the control may operate incorrectly.Note: Check the F-31 10-amp fuse in order to make sure that the fuse is not disengaged.Test Step 1. CHECK FOR AN ACTIVE DIAGNOSTIC CODE
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. 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 BATTERY VOLTAGE.
Measure the voltage at the battery posts.Expected Result:The voltage is greater than 24 V.Results:
YES - The voltage is greater than 24 DCV. Proceed to Test Step 3.
NO - The voltage is less than 24 DCV.Repair: The charging system is not correct. Check the charging system. See Special Instruction, REHS0354, "Charging System Troubleshooting". STOPTest Step 3. CHECK THE SYSTEM VOLTAGE AT THE MESSENGER MODULE
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the machine harness connector from the Messenger module .Or use spoons between contact 1 and contact 2 on the Messenger module.
Turn the disconnect switch and the key start switch to the ON position.
Run the engine at high idle.
At the machine harness connector for the Messenger module, measure the voltage between contact 1 and contact 2.Expected Result:The voltage is greater than 24 DCV.Results:
YES - The voltage is greater 24 DCV. This condition should not cause the diagnostic code.Repair: Inspect the connector. Connect the machine harness to the Messenger module. Check all connectors in the wire harness. If the CID 0168 FMI 04 remains active, replace the Messenger module. See Troubleshooting, "Electronic Control Module (ECM) - Replace".STOP
NO - The voltage is less than 24 DCV. The machine harness has failed.Repair: Check the +battery circuit and the ground circuit in the machine harness. Repair the machine harness or replace the machine harness. STOP