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

The speedometer is an analog gauge. The BCM receives the vehicle speed message from the ABS module. The ABS module uses the tire size stored in the vehicle configuration file along with wheel speed inputs to generate a vehicle speed signal. The BCM provides the vehicle speed message to the IPC.

In addition to the analog speedometer, the message center also provides a digital speed display. The IPC uses the same vehicle speed message as the speedometer to provide the message center speed display.

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.