Principles of Operation: Gauges: Speedometer
WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.
The instrument cluster receives the vehicle speed sensor (VSS) signal from the anti-lock brake system (ABS) module over the high speed CAN. The instrument cluster monitors the VSS input from the ABS module and commands the speedometer with a corresponding movement of the pointer.