Dimmable Instrument Cluster and Panel Lighting
WARNING: This page is about a different car, the 2007 Ford Pickup, 2007 Ford F550 Super Duty, 2007 Ford F450 Super Duty, and 2007 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
When the headlamp switch is in the PARKING LAMPS or HEADLAMPS ON position, the instrument panel dimmer switch uses electronic circuitry to provide a variable pulse width modulated (PWM) output to the instrument panel and all applicable switches depending on the driver-controlled level of intensity.