Dimmer Switch
WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
The illumination dimmer switch is a momentary contact switch that is integral to the headlamp switch. The headlamp switch communicates with the BCM over a LIN circuit. When the dimmer switch is pressed up or down, the requested illumination level is sent to the BCM.