CM850 Electronic Control System – FAULT CODE 427

SAE J1939 Datalink – Abnormal Update Rate


Fault Code: 427
PID: S231
SPN: 639
FMI: 9
LAMP: None

J1939 Datalink – Abnormal Update Rate. Communication between the electronic control module (ECM) and another device on the SAE J1939 data link has been lost.

Engine speed will ramp down and remain at idle.

SAE J1939 Data Link Circuit

Circuit Description

Devices such as ABS controllers, autoshift transmissions, ASR systems, electronic displays, electronic information systems, electronic service tools, and VECUs can communicate with the ECM over the SAE J1939 data link. Messages sent from the devices are received by the ECM and used for controlling the engine. The ECM also transmits information to these devices over the SAE J1939 data link.

Component Location

The ECM is located on the intake side of the engine, near the front. The SAE J1939 data link wiring and the SAE J1939 devices vary by OEM options.

Shop Talk

This fault occurs whenever the ECM has been receiving SAE J1939 datalink commands from an external OEM device and is no longer receiving the datalink commands. Possible causes of this fault include:

  • Electrical problems with the SAE J1939 data link wiring such as grounded, shorted, or open circuits
  • The ECM (or another SAE J1939 device) tying up communications by sending too many consecutive messages
  • The external OEM controlling device has failed or can no longer transmit on the datalink.

Refer to Troubleshooting Fault Code t05-427

Last Modified:  08-Jul-2010