Circuit/System Description
WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
The hood ajar switch is part of the hood latch and uses two resistors to determine the state of the hood. The body control module (BCM) apply a reference voltage on the hood ajar switch signal circuit. With the hood closed, the hood ajar switch opens and the hood ajar switch signal circuit is grounded through a 750 ohm and a 6K ohms resistor in series. When the hood is opened, the hood ajar switch closes and the hood ajar switch signal circuit is from ground through only the 750 ohm resistor. The BCM then sends a serial data message indicating the status of the hood to the instrument panel cluster (IPC), which will illuminate or displays the hood ajar indicator indicator/message as appropriate.