System overview: Control

Fig 1: Identifying Bi-Xenon Headlamps Control Input And Output Signals

Courtesy of VOLVO CARS OF NORTH AMERICA.

1.	Central electronic module (CEM)	4.	Motor, headlamp range adjustment
2.	Rear electronic module (REM)	5.	Suspension module (SUM) (vehicles with Four-C (Continuously Controlled Chassis Concept) only)
3.	Position sensor

An electric motor is controlled by the central electronic module (CEM) via a relay (ordinary high beam relay).

The motor drives a gear wheel which moves the reflector along its guides.

A sensor which detects the position of the reflector is connected to the motor.

The electronics in the motor interprets the sensor information and generates a signal
The signal is reconnected to the central electronic module (CEM).

If the reflectors are in the wrong position during high beam the reflectors are forced into a safety position;

the warning lamp (orange) lights in the driver information module (DIM)
an error message is also shown in the display in the driver information module (DIM).

If the high beam is activated with the light switch in 0 position, the high beam is only activated as long as the high beam lever is activated for a high beam flash. The headlamp switch must be in the "on" position in order for the high beam lamps to remain active.