CM850 Electronic Control System – FAULT CODE 291

Proprietary Datalink Error (OEM/Vehicle Datalink) — Abnormal Update Rate.


Fault Code: 291
PID: S248
SPN: 625
FMI: 9

Proprietary Datalink Error (OEM/Vehicle Datalink) — Abnormal Update Rate. The ECM cannot communicate with the immobilizer anti-theft system.

The immobilizer anti-theft system will not operate properly. The engine may not start.


Circuit Description

The immobilizer anti-theft device is connected to the primary engine Electronic Control Module (ECM) through a J1939 datalink network.

Messages sent from the immobilizer anti-theft device are received by the Cummins engine ECM and used for controlling the anti-theft features. The Cummins ECM and immobilizer anti-theft device must be configured properly so that proper operation of the multiplexed components will occur.

Component Location

The engine ECM is located on the intake side of the engine. The J1939 datalink wiring and location of OEM installed J1939 devices varies by OEM.

Shop Talk

This fault can occur for the following reasons:

  • When the ECM is setup properly to receive information from an immobilizer anti-theft device, but the immobilizer anti-theft device may not actually be transmitting the message for that component. This can be caused when a multiplexed component is enabled in the Cummins ECM, but the immobilizer anti-theft device source address of the VECU transmitting the component message is incorrect in the Cummins ECM, or the immobilizer anti-theft device is not setup to transmit the multiplexed component message.
  • This fault can be caused by a bad J1939 datalink connection between the immobilizer anti-theft device and Cummins ECM , a bad connection between the component and the immobilizer anti-theft device, bad immobilizer anti-theft device or bad Cummins ECM. It may be necessary to contact the OEM for proper multiplexing configuration.

On-Board Diagnostics (OBD) Information:

  • The ECM illuminates the appropriate amber or red fault lamp when the diagnostic runs and fails.
  • The ECM turns off the appropriate fault lamp when the diagnostic runs and passes.

Refer to Troubleshooting Fault Code t05-291

Last Modified:  08-Jul-2010