Cruise Control: Testing and Inspection

Improper operation can be caused by one or more mechanical, electrical, and/or vacuum problems. Before beginning diagnosis, visually inspect the following:

1. Disconnected or damaged wiring.
2. Pinched, cracked, plugged, loose, or disconnected vacuum hoses.
3. Binding or misadjusted servo-to-throttle linkage.

If any such faults are noticed, repair as needed. If the inspection shows no fault, refer to System Diagnostic Tests.

After preliminary inspection the first step in cruise control diagnosis is to determine if any trouble codes are set. This requires performing a self diagnostic system check as detailed in Computers and Controls, Testing and Inspection. If there is a cruise related computer problem, trouble codes may be set, and correcting the cause of the trouble code may also correct cruise control operation. If no trouble codes are set, see System Diagnostic Tests.