Rain/Light Sensor With Additional Functions, Component Description - GF54.21-P-6005LF
Model 217, 222
Shown on model 222 up to 31.05.2017
Location
The rain/light sensor with additional functions is located inside the windshield in the area of the inside rear-view mirror (A67).
Tasks
The rain/light sensor with additional functions is responsible for the following tasks:
- Reading in of signals
- Recording states
- Output of signals
Reading in of signals
The rain/light sensor with additional functions also reads in the following signals from the front SAM control unit (N10/6) over the rain/light sensor LIN (LIN B16):
- Activation and sensitivity of rain sensor (B38/2b1)
- Outside temperature
- Vehicle speed
- Sensitivity of light sensor (B38/2b2)
Recording states
The rain/light sensor with additional functions records the following states in the windshield area:
- Background light intensity through light sensor or light sensor "head-up display" (B38/2b4) (with code 463 (Head-up display))
- Degree of wetting over rain sensor
- Air humidity and temperature of inside of windshield through moisture/temperature sensor (B38/2b3)
Background light intensity
The light intensity of the vehicle's surroundings is measured by the light sensor.
The "head-up display" light sensor records the road brightness in the viewing direction.
Degree of wetting
The degree of wetting of the windshield is determined by the rain sensor via a transceiver path. An infrared transmitter unit beams infrared light at a defined angle to the interior of the windshield, which is almost completely reflected onto an infrared receiver when the windshield is dry. If there are water droplets on the outer surface of the windshield, a considerable part of the light is diverted. The intensity of the reflected light is correspondingly lower and the reception signal of the infrared receiver is weakened. The lower the measured light intensity the higher the degree of wetting of the windshield.
Air humidity and temperature on inside of windshield
The humidity/temperature sensor measures the relative humidity and temperature directly at the inside of the windshield and uses this to determine the dew point temperature. The surface temperature on the windshield is also determined. The comparison with the dew point temperature enables any (impending) fogging of the windshield to be detected.
Output of signals
The rain/light sensor with additional functions also sends the following signals over the rain/light sensor LIN to the front SAM control unit:
- Requirements for exterior lights
- Ambient light intensity (dimness stages)
| Wiring diagram for rain/light sensor with additional functions | Model 217, 222 as of model year 2018 | PE54.21-P-2001-97SEA | |
| Wiring diagram for overhead control panel (OCP) control unit | Model 217.3, 222 up to model year 2018 | PE54.21-P-2107-97SEA | |
| Model 217.4 up to model year 2018 | PE54.21-P-2107-97SEB |