Body Control System Description and Operation: Key-In-Ignition
WARNING: This page is about a different car, the 2003 Saturn LW300, 2003 Saturn LW200, 2003 Saturn L300, and 2003 Saturn L200. However, it is still accessible from the selected car via links, so may be relevant.
When the ignition key is seated and rotated in the ignition switch, the key-in-ignition switch contacts close grounding circuit 80. The BCM monitors the state of the key-in-ignition switch, the state of the ignition switch (OFF, ACC or RUN), and the drivers door to control the key-in-ignition chime.