Speedometer and Odometer

An electronic speedometer is standard equipment on all models. Integrated circuits control the air core speedometer and the stepper motor odometer. Removable bulb and socket assemblies provide the lighting. The socket assembly inserts into the back of the instrument cluster.

The speedometer system consists of the following components:
^ The instrument cluster
^ The Vehicle Speed Sensor (VSS) calibrator
^ The VSS
^ The related wiring

The VSS calibration is part of the VCM that changes the analog output from the VSS to a digital signal. The digital signal contains 4000 pulses per mile (PPM) for the instrument cluster. The VCM sends the signal to the speedometer through CKT 389. The VSS calibration matches to the final drive and the tire size of each vehicle. Reprogram the VCM with the proper VSS calibration if the final drive or tire size changes for any reason. The signal will not be accurate for the proper speedometer/odometer operation if the necessary change is not made. An incorrect VSS calibrator can also affect the following components:
^ The antilock brakes
^ The Vehicle Control Module (VCM) The cruise control systems

The VSS calibration is programmed into the VCM Do not service the VSS
calibrator separately.

The VSS is a permanent magnet signal generator that sends an analog signal proportional to the propeller shaft speed to the VCM. The VSS mounts to the transmission tailshaft extension housing on the two-wheel drive model. The VSS mounts to the transfer case output shaft housing on the all-wheel drive models.