Instrument Panel Cluster (IPC) Description and Operation: Speedometer
WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
The IPC displays the vehicle speed as determined by the PCM. The PCM converts the data from the vehicle speed sensor to a 4000 pulses/mile signal. The IPC uses the vehicle speed signal circuit (4000 pulses/mile), class 2 message from the PCM in order to calculate the vehicle speed. If the IPC detects a malfunction in the vehicle speed signal circuit from the PCM, the uses the class 2 message from the EBCM, indicating the vehicle speed as a backup. If the speedometer reaches (108 mph). The speedometer displays either miles or kilometers as requested by the activation of the English/metric button on the driver information center (DIC). The associated indicator (km/h or mph) illuminates.