Description & Operation: Speedometer/Odometer
The analog speedometer is electronically driven by the Vehicle Speed Sensor (VSS), located on the transaxle housing. The VSS creates eight pulses per rotation and generates an analog sine wave. A wiring harness transmits the analog sine wave signal from the VSS to an integrated converter circuit located in the analog speedometer head. The converter circuit transforms the analog sine wave signal to a digital signal, which is sent to the Powertrain Control Module (PCM), the speed control module, and to the analog speedometer.
Several areas of concern that may affect speedometer and odometer readings are:
- Tires
- Final drive ratio
- Vehicle Speed Sensor (VSS) drive and driven gears
Improper tire rolling radius, inflation pressure, temperature, and size may contribute to inaccurate system readings. Perform system accuracy testing after the tires are set to the correct pressure and after the tires are warmed for a short period. Driving at a constant speed within the posted speed limit on smooth, dry pavement will obtain the best results.
The final drive ratio of the transaxle must be known to select or to check if the proper VSS drive and driven gears are present. See Fig 1 .
The vehicle speed sensor drive gear is located inside the transaxle. The transaxle must be disassembled in order to access the VSS drive gear. The VSS driven gear, located on the end of the VSS, rotates the VSS.