CLS 55 AMG (219.376) V8-5.5L SC (113.990) (2006)
Ambient Light Sensor: Description and Operation
GF54.21-P-6000TX Rain/light Sensor, Component Description
Component Identification
Location
The rain/light sensor is located on the inside of the windshield under the inside rearview mirror.
Task
To record the light intensity and degree of wetting of the windshield
Component Identification
Principle of operation of rain sensor
Infrared light is radiated by the infrared transmitter unit (1) and led to the windshield (3). The intensity of the 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 a part of the light is scattered from the glass of the windshield (3). As a
result the intensity of the reflected light is reduced 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 degree of wetting of the windshield (3).