Cummins ISB CM850 (2003-06) Fault Code: 784 PID: SPN: 1590 FMI: 2 Loss of communication with adaptive cruise control. The ECM triggers this fault when the ?heartbeat? signal from the data bus is not received.

Possible causes:

1)The adaptive cruise hardware is not installed on the vehicle and the adaptive cruise feature has been enabled.
2)The broadcast signal from the adaptive cruise is not being received. Refer to the OEM troubleshooting and repair manual and the Adaptive Cruise Hardware Manual.

Possible repairs:

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