Cummins ISM CM870 (2003-06) Fault Code: 784 PID: SPN: 1590 FMI: 2 Adaptive Cruise Control Mode – Data Erratic, Intermittent, or Incorrect. Loss of communication with adaptive cruise control.

This fault is set active if the ECM does not receive the Heartbeat message from the adaptive cruise control unit on the SAE J1939 data link.

Possible repair:

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