Automatic Dimming Mirrors System Description - Components

Inside Mirror 

The front-facing lux level sensor is attached to the front of the mirror housing. Day or night, it senses the amount of ambient light at the front of the vehicle, and that signal is transmitted to the control unit located inside the mirror housing. The rear-facing lux level sensor is attached to the rear of the mirror housing. It senses the amount of light or glare at the rear of the vehicle, and transmits that signal to the control unit.