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To distinguish between light conditions, the rain and
light detector sensor is fitted with different light
sensors. An ambient sensor detects the light
conditions in the vehicle's immediate vicinity and a
remote sensor senses the light conditions at a
distance of up to three vehicle lengths in front in the
direction of travel.
The system detects a general decrease or increase in
brightness and switches the driving lights
on or off when the automatic headlight control
function is activated.
From the difference between both sensors' signals, the system is able to determine e.g. that the vehicle is entering a
tunnel, thereby switching on the driving lights when the vehicle enters the tunnel at the latest. The system's internal,
logical link ensures that the driving lights are only switched off once the ambient light sensor has detected an
adequate brightness value.
If the rain detector is also active in addition to the light detector, correspondingly heavy precipitation also leads to
activation of the driving lights.
Light detection function
The light detection function does not react to fog or underpasses.
In these cases, the driving lights have to be switched on manually.
Remote sen-
sor
Ambient light sensor
Optical element
Incoming ambient light
Light from
remote sources
Remote detection
Ambient light detection
Difference in brightness
less than
activation threshold value
= lights remain off
Remote detection
Ambient light detection
Difference in brightness
greater than
activation threshold value
= lights are switched on
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S338_133
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