Cummins ISB CM850 (2003-06) Fault Code: 427 PID: SID 231 SPN: 639 FMI: 9 J1939 Datalink – Abnormal Update Rate. Communication between the electronic control module (ECM) and another device on the SAE J1939 data link has been lost.

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:

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

Possible repairs:

1)Repair the damaged harness, connector or pins, if possible.