N14 CEL AND SHUTDOWN

[hhow55]

* Loose engine or chassis ground connections can cause Fault Code 343 to be logged, as well as complaints of an intermittent stumble. Pay special attention to the negative starter post connection.
* Moisture in the ECM connectors can also cause the ECM to log Fault Code 343. Refer to Service Parts Topic 95T19-12A for details on water intrusion.
* A damaged EPS can cause the ECM to log Fault Code 343 and possibly Fault Code 121 and Fault Code 115.
* Defective alternators occasionally cause FC 343. Run the engine with the alternator belt off; if the fault code becomes inactive, replace the alternator.
* Intermittent battery shorts to ground may cause the fault.
* Intermittent shorts to ground in these circuits: injector solenoids, injector harnesses, fan clutch solenoids, fan clutch wiring, engine brake solenoids, engine brake wiring, OEM installed engine speed sensors, flywheel housing and associated wiring, datalink wiring, and fuel shutoff solenoid or wiring may cause intermittent Fault Code 343.
* To determine if conducted electrical noise through the grounds is causing the Fault Code 343, unbolt the ECM, and move it away from the engine block so that it is isolated from the engine block ground. If the fault is not duplicated, troubleshoot for the source of the electrical noise.

found this on a cummins site