Central Electronic Module (CEM): Design: Headlamps
The headlamps are operated via the light switch module (LSM), which is located on the dashboard at the side of the steering wheel. The light switch module (LSM) is connected to the central electronic module (CEM) via LIN communication. Low and high beam are operated by moving the left-hand control stalk toward the steering wheel.
Low beam is powered directly by the central electronic module (CEM). High beam is powered via a directly connected relay on the central electronic module (CEM). The level of the supply voltage to the low beam is regulated by the central electronic module (CEM). When the supply voltage is sufficient (in excess of 13 V), pulse width modulation is used to maintain the voltage level at 13.0 V +/- 0.2 V. This does not apply to cars with Bi-Xenon lamps.
Cars with Bi-Xenon lamps are powered directly via the central electronic module (CEM) without pulse width modulation.
To detect problems with the low beam, the central electronic module (CEM) reads the power consumption of the circuit. If this falls below a certain threshold value a fault will be indicated. The general warning lamp lights in the driver information module (DIM) and a text message is displayed.
Right and left-hand asymmetric lamps
The right and left-hand asymmetric lamps are adjusted mechanically using a simple operation. A lever is accessible when the rear cover on the headlamp housing is opened.
Headlamp range adjustment (certain markets) (for vehicles without automatic headlamp range adjustment)
There are two motors which angle the headlamps upwards or downwards to control the range of the beam. The motors are integrated in the headlamps.
The motors are controlled by a thumb wheel which is located in the light switch module (LSM) on the dashboard by the side of the steering wheel.
If the thumb wheel is turned, information is transmitted to the motors which adjust the headlamps accordingly.