Device Power
WARNING: This page is about a different car, the 2005 Saturn L300. However, it is still accessible from the selected car via links, so may be relevant.
Battery 1 voltage is supplied to the BCM by circuit 2540. Battery 2 voltage is supplied to the BCM by circuit 1640. These inputs are internally monitored by the BCM for proper operating voltage. The proper operating voltage range is from 9-16 volts.