Gauge Pack, Instrument Cluster: Operation: Operation: Gauges: Speedometer

The speedometer gives an indication to the vehicle operator of the vehicle road speed. This gauge is controlled by the IPC circuit board based upon programming and electronic messages received from the BCM. The BCM provides the vehicle speed information across the CAN-B, and CAN-C data buses for use other modules within the vehicle.

The IPC circuitry controls the gauge needle position and provides the following features:

• Vehicle Speed Message  - Each time the IPC receives an electronic vehicle speed  message from the BCM it will calculate the correct vehicle speed reading and position the gauge needle at that relative speed position on the gauge scale. The IPC will receive a new message and reposition the gauge pointer accordingly. The gauge needle will continually be positioned at the relative vehicle speed position on the gauge scale until the vehicle stops moving, or until the ignition switch is turned to the OFF position, whichever occurs first.
• Communication Error  - If the IPC fails to receive a speed message, it will hold the gauge needle at the last indication for about three seconds, or until the ignition switch is turned to the OFF position, whichever occurs first. After three seconds, the gauge needle will return to the left end of the gauge scale.

The PCM continually monitors the vehicle speed sensor to determine the vehicle road speed. The PCM then sends the proper vehicle speed messages to the BCM over the CAN data bus. The speedometer can only be serviced as a unit with the instrument cluster.