CM850 Electronic Control System – FAULT CODE 341

Engine Control Module Data Lost – Data Erratic, Intermittent or Incorrect


Fault Code: 341
PID: S253
SPN: 630
FMI: 2/2
LAMP: Amber

Engine Control Module Data Lost – Data Erratic, Intermittent or Incorrect. Severe loss of data from the ECM.

Possible no noticeable performance effects, engine dying or hard starting. Fault information, trip information, and maintenance monitor data can be inaccurate.

Unswitched Battery Supply Circuit

Circuit Description

The Electronic Control Module (ECM) receives constant voltage from the batteries through the unswitched battery wires that are connected directly to the positive (+) battery post. There is a single 30-ampere fuse in the unswitched battery wires to protect the engine harness from overheating. In marine applications this is a 25 ampere fuse on 12 VDC systems and a 15 ampere fuse on 24 VDC systems. The ECM receives switched battery input through the vehicle keyswitch wire when the vehicle keyswitch is turned on. The battery return wires are connected directly to the negative (-) battery post. Pins 2 and 3 are optional circuits possibly not used by the OEM. In marine applications only circuits 1 and 3 are use for unswitched battery. Refer to the OEM circuit diagram or wiring diagram for detailed information on these circuit.

Component Location

The ECM is located on the left side of the engine, near the front of the engine. The ECM is connected to the battery by the ECM power harness. This direct link provides a constant power supply for the ECM. The location of the battery will vary with the OEM. Refer to the OEM troubleshooting and repair manual.

Refer to Troubleshooting Fault Code t05-341

Last Modified:  08-Jul-2010