Hood Ajar Switch
WARNING: This page is about a different car, the 2017 Lincoln Navigator and 2017 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
The hood ajar switch is a single pole switch that is normally closed when the hood is closed, routing the voltage signal to ground. When the hood is opened, the hood ajar switch opens, interrupting the signal to indicate an open hood.
The BCM sends a voltage reference signal to the hood ajar switch, and based on the input, the BCM determines if the hood is open or closed.