Principles of Operation: Speedometer/Odometer
WARNING: This page is about a different car, the 2003 Ford RV Cutaway, 2003 Ford Econoline, 2003 Ford E550 Super Duty, 2003 Ford E450 Super Duty, and 2003 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
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).