R 63 AMG (251.177) V8-6.3L (156.980) (2007)
Ambient Light Sensor: Description and Operation
GF54.21-P-6000RT Rain/light Sensor, Component Description
Component Identification
Location
The rain/light sensor is located on the inside of the windshield below the inside rearview mirror.
Task
To measure the light intensity and degree of wetting of the windshield
Function principle of rain sensor
Infrared light is beamed from the infrared transmitter unit (1) and is directed to the windshield (3). The intensity of light reflected at the windshield (3) is
measured by the IR-receiver unit (2).
If the windshield (3) is dry in the area of the rain/light sensor (picture A), then the light is almost completely reflected and the IR-receiver unit (2)
measures a high light intensity. If the windshield (3) is wet in the area of the rain/light sensor (picture B), then part of the light is scattered out of the
glass of the windshield (3). As a result the intensity of the reflected light reduces and the IR-receiver unit (2) measures a lower light intensity.
The light intensity measured by the IR receiver (2) is a measure for the quantity of water on the windshield (3). The lower the measured light intensity
the greater the amount of water on the windshield (3). As of production period 01.06.2006 the sensitivity of the sensor can be preset via the combination
switch (S4) with the positions "intermittent 1" and "intermittent 2".