Instrument Panel Cluster (IPC) Description and Operation: Voltmeter
WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
The IPC displays the vehicle voltage based on the information from the BCM. The IPC uses class 2 serial data information from the BCM to provide a voltage level indication on the voltmeter.