Rain/rain/light sensor
WARNING: This page does not describe the selected car, but rather 45 other vehicles, including the 2016 BMW M5, 2016 BMW 550i xDrive, 2016 BMW 550i, 2016 BMW 535i xDrive, and 2016 BMW 535i. However, it is still accessible from the selected car via links, so may be relevant.
The rain/light sensor measures the ambient brightness. After twilight, the front electronic module (FEM) switches on the low-beam headlights (prerequisite: light switch is in switch position "A"). The high-beam assistant (FLA) can only be activated when the low-beam headlights are switched on.