Operation CHARM: Car repair manuals for everyone.

Speedometer Module: Description and Operation

The speedometer is a road speed indicator. The base cluster contains a season (total mileage) odometer. The gage cluster is equipped with both a trip odometer and season odometer. A vehicle speed sensor (VSS) (permanent magnet generator) located on the transaxle inputs to the engine control module (ECM) whenever the transaxle differential carrier turns.

The odometer(s) are driven by a stepper motor in the cluster. The odometer discs are geared so that as any one disc finishes a complete revolution, the next disc to the left is turned one-tenth of a revolution. The trip odometer (gage cluster) may be reset to zero when the driver pushes the trip odometer reset pin.