Road Test
Perform a vehicle road test to verify reports of speed control system malfunction. The road test should include attention to the speedometer. Speedometer operation should be smooth and without flutter at all speeds.
Flutter in the speedometer indicates a problem which might cause surging in the speed control system. The cause of any speedometer problems should be corrected before proceeding. Refer to INSTRUMENT CLUSTER - SERVICE INFORMATION for speedometer diagnosis.
If a road test verifies an inoperative system, and the speedometer operates properly, check for:
- A Diagnostic Trouble Code (DTC). If a DTC exists, conduct tests per the Powertrain Diagnostic Procedures.
- A misadjusted brake (stop) lamp switch. This could also cause an intermittent problem.
- Conduct electrical test at PCM.
CAUTION:
When test probing for voltage or continuity at electrical connectors, care must be taken not to damage connector, terminals or seals. If these components are damaged, intermittent or complete system failure may occur.