Set Speed Fluctuates
WARNING:
Disable air bag system before working around steering column or removing any air bag system component. See appropriate AIR BAG RESTRAINT SYSTEM article.
- While observing speedometer, test drive vehicle at a constant speed of 40-55 MPH. If speedometer does not display a constant speed, diagnose and repair speedometer as necessary. See appropriate INSTRUMENT PANEL article.
If speedometer displays a constant speed, go to next step.
- Test speed control servo. See SPEED CONTROL SERVO under COMPONENT TESTING . If speed control servo is okay, go to next step. If speed control servo is not okay, replace speed control servo.
- Turn ignition off. Disconnect instrument cluster connector and speed control amplifier connector. Measure resistance of Green/Yellow wire between instrument cluster connector and speed control amplifier connector. Measure resistance of Green/Yellow wire between instrument cluster connector and ground. Resistances should be less than 5 ohms between instrument cluster and amplifier, and greater than 10 k/ohms between instrument cluster and ground. If resistances are as specified, replace speed control amplifier. If resistances are not as specified, repair Green/Yellow wire.