ALTERNATOR GROUP 4N4540 - Caterpillar

Note: If the vessel is equipped with a Multi-Station Control System (MSCS), refer to Service Manual, RENR7651, "Marine Multi-Station Control System" for the proper troubleshooting procedure.Note: Use this procedure only if the engine shut down completely and it was necessary to restart the engine.Probable Causes
Diagnostic codes
Electrical connections
Remote shutdown switch
Fuel supplyNote: If the problem only occurs under certain conditions such as high engine speed, full load or engine operating temperature, then perform the test under those operating conditions.Recommended Actions
Diagnostic Codes
Certain diagnostic codes may cause the engine to shutdown. Connect the electronic service tool and check for active codes and/or logged codes. Troubleshoot any codes that are present before continuing with this procedure.Electrical Connections
Check the following connectors and the associated wiring for damage, for abrasion, for corrosion and for incorrect attachment:
ECM connectors
Customer connectors
Engine speed/timing sensors
unit injector connectorsRefer to Troubleshooting, "Electrical Connectors - Inspect" for additional information.
Check the battery connections at the customer connector and the P1 ECM connector. Perform a pull test on all of the wires that are related to the battery connections. Refer to the engine's Electrical Schematic for the appropriate terminals. The wires should remain in the connectors during the pull test. Refer to Troubleshooting, "Electrical Connectors - Inspect".
The problem may occur when the engine is warmed up. Then as the engine cools, the problem may disappear. The circuit breakers may be exceeding the trip point because of the overheating. Check the circuit breakers on the engine. Reset the circuit breakers, if necessary.
Aftermarket engine protection devices can interrupt power to the ECM. Check for correct installation and operation of aftermarket engine protection devices. It may be necessary to bypass aftermarket devices in order to continue testing.Fuel Supply
Check for a problem with the fuel supply and verify the fuel pressure. Verify that the fuel pressure sensor is installed. Refer to Systems Operation/Testing and Adjusting, "Fuel System" for additional information.Remote Shutdown Switch
Access the status screen on the electronic service tool that displays the remote shutdown switch status. The remote shutdown switch status on the electronic service tool is called "User Shutdown".
Table 1
"User Shutdown" Status     Switch Status     Measured Voltage at P61-36    
ON     Negative battery     <0.9 VDC    
OFF     Open Circuit     >10 VDC    If the voltage is not in the proper range, refer to Troubleshooting, "Switch Circuits - Test".