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 CCN circuit board based upon programming and electronic messages received from the Totally Integrated Power Module (TIPM). The TIPM is provided the vehicle speed information across the CAN data bus by either the PCM, the ESP module or the ABS module.

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

• Vehicle Speed Message  - Each time the CCN receives an electronic vehicle speed  message from the PCM it will calculate the correct vehicle speed reading and position the gauge needle at that relative speed position on the gauge scale. The CCN will receive a new message and reposition the gauge pointer accordingly about every 88 milliseconds. 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 CCN 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 CCN. For further diagnosis of the speedometer or the CCN circuitry that controls the gauge. See Electrical/Instrument Cluster - Diagnosis and Testing . The speedometer is serviced as a unit with the instrument cluster.