P54.21-3940-78
B38/2 | Rain/light sensor with additional functions |
Location
The rain and light sensor is located on the inside of the windshield in the area of the inside rearview mirror.
Task
The rain and light sensor detects the following conditions:
Background light intensity
The light sensor records the ambient light intensity.
The Head-up Display light sensor (vehicles with Head-up Display) records the road brightness in the viewing direction.
Degree of windshield wetting
The rain sensor detects the degree of wetting of the windshield. An infrared transmitter unit beams infrared light at a defined angle to the interior of the windshield, which is almost completely reflected when the windshield is dry. If there are water droplets outside on the windshield, a considerable part of the infrared light is diverted. The intensity of the reflected infrared light is correspondingly lower. 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. The data are used to calculate the dew point temperature and the surface temperature of the windshield. This enables any (imminent) windshield fogging to be detected.
Intensity of solar radiation
The sun sensor records the intensity of the solar radiation in the vehicle. Depending on this, the control of the climate control adapts the vehicle interior temperature and the blower setting.
The rain and light sensor is networked with the front central controller unit.
To reference the signals from the integrated sensors, the rain and light sensor evaluates, among others, the following information:
Terminal status of terminal 15
Outside temperature
Vehicle speed
Windshield wiper, status
Request for sensitivity of light sensor
Request for sensitivity of rain sensor
The rain and light sensor also sends the following signals:
Ambient light intensity (dimness stages)
"Switch on low beams" request
Windshield wiper request
Dew point temperature, surface temperature of windshield
Intensity of solar radiation
Diagnosis information
Structure
The following sensors are integrated into the rain and light sensor:
Rain sensor
Light sensor
Humidity/temperature sensor
Head-up Display light sensor (vehicles with Head-up Display)
Sun sensor