The external lighting conditions are measured by an optoelectronic detector. Using an upstream filter glass, the sensor records special wavelengths in order to distinguish between artificial light and daylight. The ambient light and front-end lighting are measured by two sensors, which function independently of one another.
The illuminance around the vehicle is recorded using the ambient light sensor over a large spatial angle (Figure 6).
The light intensity in front of the vehicle is recorded with the front-end light sensor over a small angle (Figure 7).
In order to do this, the sensor's receiver characteristics must be matched to the installation situation. A special algorithm uses the sensor data and by including further information from the vehicle electronics detects various lighting conditions (day, night, dusk or passing through a tunnel/bridge) and switches the daytime running light on or off accordingly.