Circuit Description
WARNING: This page is about a different car, the 2007 Pontiac Montana SV6, 2007 Chevrolet Uplander, and 2007 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.
The instrument panel cluster (IPC) monitors the battery positive voltage and battery negative circuit voltage to determine if it is between 9-15 volts.