Key Cylinder Unlock
WARNING: This page is about a different car, the 2004 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.
The BCM will unlock all of the doors after detecting a door lock cylinder switch in the Unlock position for greater than 1 second. The BCM supplies battery positive voltage, through the door lock key switch unlock signal circuit, to the door lock cylinder switch. The door lock cylinder switch is grounded, through the ground circuit, to a body ground stake. When the door lock cylinder switch is activated to the Unlock function, the normally open contacts of the two circuits are closed, and the BCM interprets the flow of voltage as an unlock doors input.