Circuit/System Description
WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
The starter/generator control module (SGCM) monitors the 14-volt power module current sensor for an overcurrent condition to protect the MOSFET. In the hardware an overcurrent protection circuit is used to limit the current, and software monitors for an overcurrent reading in the sensor.