Troubleshooting Hints

SYSTEM DIAGNOSIS
The cruise control system is integrated with the PCM producing a system with enhanced diagnostic capabilities as well as performance. Cruise switch signals go directly to the PCM which uses engine control sensors to evaluate and command cruise movement and direction, enable/disable of the cruise module clutch. PCM control and Class II DLC allow diagnosis of the system with a Scan tool. Diagnostic trouble code information will be stored in the PCM malfunction history memory when faults are detected.

Diagnosis of the system is performed with the use of a Scan tool. Through special test functions the Scan tool is capable of controlling the cruise module. Control of the function is allowed if engine is not running and vehicle is stopped (engine RPM and vehicle speed equal zero). This can be used to verify the PCM is capable of controlling the cruise module. Complaint/condition charts are also available to aid in diagnosis. Since the system is "self-diagnostic" a failure in the system should result in diagnostic trouble codes (DTCs) being set. These DTCs have the same capability as engine control DTCs and will show PASS/FAIL data and failure parameter data. As is the case with electronic engine controls the DTCs have specific flow charts and descriptions for diagnosis. There is also a "CRUISE CONTROL INOPERATIVE" chart for use when no DTCs are set. For Scan tool parameter descriptions refer to "Vehicle on-Board Diagnostics".