Function Of The Rain Sensor - Audi A6 2005 - Electrics Service Training

Convenience electrics

Function of the rain sensor

The rain sensor uses the physical light refraction
principle to register the amount of moisture on the
windscreen. The circular LEDs integrated in the
sensor emit infrared light through the windscreen
from within the interior of the vehicle.
If the windscreen is dry, the infrared light is
reflected on the surface of the glass.
The photodiode integrated in the centre of the
sensor thus records a high light intensity.
If the windscreen is covered with moisture, the
optical properties on the surface of the glass
change. Light now emerges from the windscreen
surface through the light refraction caused by water
drops. As a result, less light is reflected back and the
photodiode records a lower light intensity (light
dispersion principle).
Diagnosis
The control unit for on-board power supply J519 is
used for diagnostic procedures on the sensor for
rain and light detection.
50
LEDs
Photodiode
326_091
326_080
Windscreen surface
LED
Photodiode
LED
326_093