Reverse Gear Switch
WARNING: This page does not describe the selected car, but rather 46 other vehicles, including the 2008 BMW M5, 2008 BMW 650i, 2007 BMW Z4, 2007 BMW M6, and 2007 BMW M5. However, it is still accessible from the selected car via links, so may be relevant.
The main-beam headlights are not switched on if reverse gear is engaged. In a manual-shift car, the reverse gear switch supplies the "reverse gear engaged" information.
The reverse gear switch sends this information to the light module.