Test Description

Refer to the diagnostic charts if the cruise control does not operate.

NOTE: If any diagnostic codes are displayed, or if diagnostics cannot be entered, refer to COMPUTERIZED ENGINE CONTROLS first.




The operation of the cruise control system is integral with the Body Control Module (BCM) or Engine Control Module (ECM). The BCM or ECM monitors the cruise control system and other systems by comparing the actual operating conditions to standard values stored in memory. When certain system malfunctions are detected, a three digit trouble code is stored in the BCM memory. These trouble codes can be displayed to aid in system diagnosis. In this manner, the speed control system can be diagnosed by accessing fault codes, if they exist, that pertain to the speed control system.


Codes other than those described below may be stored in the BCM memory and displayed when the system is accessed to diagnose cruise control malfunctions. When the ECM or BCM sees certain trouble codes in memory, it will disengage and prevent cruise control operation. It may be necessary to diagnose these codes and identify the non-speed control related failure in order to ensure proper speed control system operation.