CM850 Electronic Control System – FAULT CODE 784

Adaptive Cruise Control – Error


Fault Code: 784
SPN: 1590
FMI: 2
LAMP: None

Loss of communication with adaptive cruise control. The ECM triggers this fault when the “heartbeat” signal from the data bus is not received.

Adaptive cruise control will not operate. Cruise control possibly will not operate properly.

Cruise Control Circuit

Circuit Description

The adaptive cruise control unit communicates with the electronic control module (ECM), sending and receiving vehicle speed control messages through the SAE J1939 data link.

Component Location

The adaptive cruise control is a feature in INSITE™ electronic service tool. Refer to the OEM troubleshooting and repair manual for Adaptive Cruise Control Hardware.

Shop Talk

Two conditions can cause this problem:

  • The adaptive cruise hardware is not installed on the vehicle and the adaptive cruise feature has been enabled.
  • 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.

Refer to Troubleshooting Fault Code t05-784

Last Modified:  08-Jul-2010