Circuit/System Description
WARNING: This page is about a different car, the 2011 GMC Yukon, 2011 Chevrolet Tahoe, and 2011 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
The hybrid powertrain control module uses ignition 1 circuit terminal voltage to monitor the 12V system voltage. Ignition 1 circuit voltage also powers several of the internal drive motor generator power inverter control module drive motor generator power inverter module components.