Instrument Panel Cluster (IPC) - System Operation and Component Description: Speedometer

WARNING: This page is about a different car, the 2015 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

The IPC receives the vehicle speed data from the GWM over the High Speed Controller Area Network 3 (HS3-CAN). The GWM receives the vehicle speed message from the PCM over the High Speed Controller Area Network 1 (HS1-CAN). The PCM receives the wheel speed data from the ABS. The PCM uses tire size stored in the vehicle configuration file along with wheel speed inputs to generate a vehicle speed signal.

The IPC provides a tolerance that allows the speed indication to display between 3% below and 7% above the actual vehicle speed. This means that with an actual vehicle speed of 97 km/h (60 mph), the speedometer can indicate between 94-103 km/h (58-64 mph). Incorrect tire size or tire size configuration could potentially affect the speedometer accuracy.