Faulty Vehicle Speed Sensor (VSS)
Vehicle Speed Sensor (VSS) harness is open or shorted
Vehicle Speed Sensor (VSS) circuit poor electrical connection
Engine Light ON (or Service Engine Soon Warning Light)
The Vehicle Speed Sensor (VSS) provides vehicle speed information to the Engine Control Module (ECM). The VSS is a permanent magnet generator. The sensor is mounted in the transfer case facing the rear internal gear which is splined to the output shaft assembly. As the output shaft and internal gear rotate, the toothed rotor of the internal gear produces AC voltage as the rotor teeth pass through the magnetic field of the sensor. The AC voltage level and the number of pulses increase as the speed of the vehicle increases. The ECM converts the voltage to vehicle speed. The ECM uses the output shaft speed signal to determine shift timing, as well as transfer case range.