CM850 Electronic Control System – FAULT CODE 442

Battery 1 Voltage – Data Valid but Above Normal Operational Range – Moderately Severe Level


Fault Code: 442
PID: P168
SPN: 168
FMI: 0/16
LAMP: Amber

Battery 1 Voltage – Data Valid but Above Normal Operational Range
– Moderately Severe Level. ECM supply voltage is above the maximum system voltage level.

Possible electrical damage to all electrical components.

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 one 30-amp fuse in the unswitched battery wire to protect the OEM harness. In marine applications this is a 25 ampere fuse on 12V systems an a 15 ampere fuse on 24V 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.

Component Location

The ECM is located on the intake side of the engine. The ECM is connected to the battery by the OEM harness. This direct link provides a constant power supply for the ECM. In marine application only circuits 1 and 3 are use for unsiwtchd battery. The location of the battery will vary with the original equipment manufacturer (OEM). Refer to the OEM manual for battery location.

Shop Talk

This fault code is logged when the ECM battery supply voltage exceed 36 volts. Causes of this fault code include:

  • Faulty alternator or regulator that is overcharging the system
  • Batteries connected in series instead of parallel
  • Incorrect jump-starting procedure.

Refer to Troubleshooting Fault Code t05-442

Last Modified:  08-Jul-2010