The Automatic Light-On function increases safety by automatically turning on your headlights at dusk or when you drive through a tunnel. This provides good visibility and ensures your car is seen by other road users.
The system processes the signals from different light sensors located in the base of the rear view mirror. Several directional sensors pointing horizontally and with a spread angle of approximately 10 degrees detect the brightness in the direction of travel. The sensors are directed to different areas, so that they don’t mistakenly interpret the light from oncoming cars as daylight, for example.
An ambient light sensor detects the light inside your car. This means the Automatic Light-On can distinguish whether your vehicle is approaching a tunnel or only a bridge. For example, the system identifies a tunnel when the direction sensors register darkness in front of the car, and when you enter the tunnel, the ambient light sensor "confirms" the darkness.