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Adaptive Cruise Control Mode – Data Erratic, Intermittent, or Incorrect
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Overview
| CODE | REASON | EFFECT |
| Fault Code: 784 PID: S145 SPN: 1590 FMI: 2/2 LAMP: None SRT: |
Adaptive Cruise Control Mode – Data Erratic, Intermittent, or Incorrect. Loss of communication with adaptive cruise control. |
Adaptive cruise control will not operate. Standard cruise control may not operate. |
 ISX and ISM – Adaptive Cruise Control Circuit
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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 location of the adaptive cruise control unit will vary by original equipment manufacturer (OEM). Refer to the OEM service manual for specific location.
Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position.
Conditions for Setting the Fault Codes
The ECM does not receive a valid J1939 message from the adaptive cruise control module for more than one second.
Action Taken When the Fault Code is Active
- The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
- The adaptive cruise control will not operate.
Conditions for Clearing the Fault Code
The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.
Shop Talk
Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM. Refer to Procedure 019-032 (ECM Calibration Code) in Section 19 in the corresponding Troubleshooting and Repair Manual for the engine being serviced.
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.
If Adaptive Cruise Recovery is enabled, the driver can toggle the cruise enable switch from the OFF position to the ON position two times to get regular cruise control to operate and Fault Code 784 will go inactive. At the next key cycle, if the Heartbeat message is still not present, Fault Code 784 will go active.
Refer to Troubleshooting Fault Code t05-784
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