Principles of Operation: Speedometer/Odometer

On vehicles equipped with gasoline engines, the speedometer/odometer is hardwired to the powertrain control module (PCM). The vehicle speed signal is transmitted directly from the PCM to the speedometer/odometer. The PCM receives its signal from the output shaft speed sensor (OSS).

On vehicles equipped with diesel engines, the speedometer-odometer is hardwired to the vehicle speed sensor (VSS).