GMC Envoy Speedometer Problemsby Andrea Stein
A vehicle speedometer is an instrument gauge designed to measure the engine RPM of a vehicle and display it. The speedometer on a GMC Envoy SUV (sports utility vehicle) can develop problems, some of which may be easily diagnosed and resolved.
A bad speed sensor in a GMC Envoy SUV can cause erratic speedometer readings. Check the speed sensor for corrosion on the electrical contacts and clean them as needed. Connect the leads of an Ohmmeter to each contact to check the sensor’s charge. Refer to your GMC owner’s manual for the speed sensor’s voltage value. If the value specified in the manual is higher than determined by the Ohmmeter, replace the speed sensor.
The GMC Envoy speedometer stepper motor, an electromechanical motor that moves in increments instead of continuously, can develop a crack in its gears, resulting in intermittent speedometer function. Remove the speedometer's stepper motor and inspect the gear assembly. If you discover any cracked gears, replace the stepper motor.
If you hear a scraping noise when the GMC Envoy speedometer needle moves, kinked speedometer cabling may be to blame. Remove the speedometer cable and smooth out any kinks. If the cable appears worn or damaged, replace it.