Both sensors are located on the windscreen alongside the rear view mirror, these sensors activate the headlights automatically and windscreen wipers. The rain sensor activates the windscreen wipers automatically if it starts to rain or if there is any other moisture on the windscreen and adapts the wiper interval to match the amount of rain. How it works: light-emitting diodes inside the rain sensor emit an invisible infrared light which is reflected by the outside surface of the windscreen and measured by photodiodes. If the full amount of light returns to the photodiode then the windscreen is dry. A film of water or drops on the windscreen break up the light emitted. As the measuring process is permanent, the electronics can control the wiper intervals perfectly. Moreover a light sensor automatically activates the headlights when the sun goes down, or when you enter a tunnel as soon as the level of light detected by the sensor is dropping.
