The Automatic Headlamp Leveling System is used primarily in European Countries, however, as the usage of HID and the concerns of the glare they may emit increase, you may see them travel to this side of the pond. 

Consisting of a Leveling Module (can't we do anything without a module?), Leveling Actuators for each Headlight and either discreet height sensors or sensors used from an active suspension system (sending info on a data line). 

The automatic headlamp leveling system automatically maintains the vertical alignment of the headlamps when the vehicle load and driving conditions change. The headlamp leveling module receives inputs from the front and rear suspension position sensors to determine vehicle pitch. The suspension position sensors send an output to the headlamp leveling module as the vehicle suspension compresses and rebounds. The headlamp leveling module calculates the difference in vehicle pitch and sends a command to the headlamp leveling actuators. The headlamp leveling actuators drive the headlamps to the position commanded by the headlamp leveling module. On some models the headlamp leveling system also monitors the performance of the high intensity discharge (HID) bulb and ballast. When the headlamp switch is placed in the ON position the headlamps will go down, and then back up to the center position. 

Until we see use here in the states, chances are you will not have to deal with one of these systems...yet.

Mik Stubing Lead Instructor - Northeast Region