| The main beam assist is activated if the light switch -E1- is set to AUTO and the turn signal switch -E2- is then pushed forwards once. The position of the turn signal switch -E2- is scanned by the steering column electronics control unit -J527- and transmitted across the convenience CAN bus to the onboard supply control unit -J519-. |
| A headlight symbol with an »A« lights up in the instrument cluster to indicate to the driver that the main beam assist is active. The blue main beam symbol lights up in addition when the main beam headlights are activated. |
| A CMOS camera is installed in the base of the interior mirror so that the main beam headlights can be switched on and off automatically in addition to the dipped beam headlights (see Chapter 2). The associated evaluation electronics, in the form of the main beam assist control unit -J844-, are integrated in the automatic anti-dazzle interior mirror -Y7-. |
| The CMOS camera takes a white picture and a red picture in order to determine the current traffic situation and ambient conditions. The main beam assist control unit -J844- uses these pictures to generate the information as to whether the main beam headlights are to be activated or deactivated. |
| If vehicles travelling in the same or opposite direction are detected a short distance in front of the vehicle, the request to dip the headlights is transmitted across the CAN bus to the onboard supply control unit -J519-. Similarly, a request to dip the headlights is also transmitted if the road speed drops below a specified minimum or if the ambient brightness exceeds a defined threshold level due to daylight or bright street lighting. If no dipped headlights condition applies, a main beam request is transmitted. |
| If the automatic main beam control is active, and if the road speed exceeds a specified threshold level, and if the onboard supply control unit -J519- concurrently receives a command from the rain and light sensor -G397- to switch on the dipped headlights, then the onboard supply control unit -J519- activates the left and right headlight main beam bulbs -M30- and -M32- or the left and right dipped beam screens -V294- and -V295-, according to the main beam setting recommended by the main beam assist control unit -J844-. |
| The main beam is not activated if the rain and light sensor -G397- has not transmitted a command to switch on the dipped headlights. If the main beam has been activated by the main beam assist and the rain and light sensor -G397- then transmits the command to switch off the headlights, the main beam is also deactivated. |
| If the driver prefers a different setting to that currently requested by the main beam assist, he can switch the main beam on or off manually. |
| If the main beam assist control unit -J844- is transmitting a dipped beam request, the driver can switch on the main beam by pushing the turn signal switch -E2- forwards once. The main beam assist is now deactivated temporarily. The main beam assist is re-activated if the driver pushes the turn signal switch -E2- forwards again. If the driver pulls back the turn signal switch -E2- after the temporary deactivation, the headlights are dipped and the main beam assist is deactivated permanently. |
| If the main beam is activated in response to a request from the main beam assist, the driver can dip the headlights by pulling back the turn signal switch -E2- once. This permanently deactivates the main beam assist. If the driver pushes the turn signal switch -E2- forwards once when the main beam is active, the main beam assist is deactivated temporarily and the main beam remains on. The main beam assist is re-activated by pushing the turn signal switch -E2- forwards again. If the turn signal switch -E2- is pulled back once after a temporary deactivation, the main beam assist is deactivated permanently. |
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