Rain/light sensor with additional functions, component description - GF54.21-P-6005RF
MODEL 205, 253
Shown: Model 205.0
Location
The rain/light sensor with additional functions is on the inside of the windshield in the area of the inside rearview mirror (A67).
Task
The following sensors are integrated in the rain/light sensor with additional functions:
- Rain sensor (B38/2b1)
- Light sensor (B38/2b2)
- Humidity and temperature sensor (B38/2b3)
- Head-up display light sensor (B38/2b4) (with CODE 463 (Head-up display))
- Sun sensor (B38/2b5)
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 function communicates via the rain/light sensor-LIN (LIN B16) with the front SAM control unit (N10/6). The front SAM control unit sends the following signals, amongst others, via the rain/light sensor LIN to the rain/light sensor with additional functions:
- Activation and sensitivity of rain sensor
- Outside temperature
- Vehicle speed
- Sensitivity of light sensor
Recording states
The sensors integrated in the rain/light sensor with additional functions record the following states in the windshield area:
- Background light intensity
- Degree of windshield wetting
- Air humidity and temperature on inside of windshield
- Intensity of solar radiation
Background light intensity
The light intensity of the vehicle's surroundings is detected by the light sensor.
The head-up display light sensor (with CODE 463 (Head-up display)) detects the brightness of the road in the viewing direction.
Degree of wetting
The degree of wetting of the windshield is determined by the rain sensor using a transceiver distance. 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 infrared light is diverted. The intensity of the reflected infrared light is correspondingly lower and the reception signal of the infrared receiver is weaker. 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 and temperature sensor measures the relative air humidity and the temperature directly at the inside of the windshield. From these values, the rain/light sensor with additional functions calculates the dew point temperature. Comparison of the windshield surface temperature with the dew point temperature enables (impending) fogging to be detected.
Intensity of solar radiation
The sun sensor detects the intensity of the solar radiation on the vehicle. The interior temperature and blower output are adapted depending on this. In the event of one-sided solar radiation, an adequate temperature difference is set between the left and the right regulated specified temperatures.
Output of signals
The rain/light sensor with additional functions sends the following signals, amongst others, via the rain/light sensor LIN to the front SAM control unit:
- "Switch on low beams" request
- Wiper stage
- Ambient light intensity (dusk/dawn level)
- Solar radiation
- Dewpoint temperature
| Wiring diagram for overhead control panel (OCP) control unit | PE54.21-P-2107-97FBA |