Bi-Xenon headlights

Fig 1: Identifying Bi-Xenon Headlight Communication System & Components

Courtesy of VOLVO CARS OF NORTH AMERICA.

1.	Motor, high/low beam	Power supply via relay. Feedback PWM signal gives central electronic module (CEM) information on reflector position.
2.	Motor, headlight levelling	Regulated by central electronic module (CEM) via PWM signal.
3.	Position sensors	Inductive sensor that transmits an analogue signal (voltage) to the rear electronic module (REM) (not vehicles equipped with Four-C (Continuously Controlled Chassis Concept)). On vehicles with Four-C, the signal travels via the suspension module (SUM).
4.	Ballast	High voltage regulator for contact and lamp.
5.	Gas discharge lamp	Socket