Brief Description Of Components
The following components and control units provide input signals for the main-beam assistant:
- Light switch
The main-beam assistant can be activated only when the light switch is in position "A".
"A" stands for "automatic headlight control".
- Turn-signal/main-beam switch
The main-beam assistant is activated and deactivated by mans of the turn-signal/main-beam switch.
See the section entitled "OPERATION " below.
- Rain-light sensor
The rain-light sensor measures the brightness of the ambient light. The light module switches the dipped headlights on when daylight fails.
The main-beam assistant can be activated only when the dipped headlights are on. The precondition is that the light switch must be in the "A" position.
- Wheel-speed sensors
Each of the wheel-speed sensors measures the circumferential speed of an individual wheel. The DSC control unit (DSC: Dynamic Stability Control) uses these input signals to calculate the car's road speed.
The main-beam headlights are switched on when the car's road speed is above 50 km/h.
The main-beam headlights are switched off when the car's road speed is below 38 km/h.
- DSC sensor
The DSC sensor registers lateral acceleration and calculates the yaw rate.
("Yaw" is the movement of the vehicle about the vertical axis, e.g. when the car is cornering).
The main-beam assistant uses the yaw rate to improve evaluation when the car corners. The DSC sensor is underneath the driver's seat. For safety reasons, cars with active front steering have a second DSC sensor underneath the front passenger's seat.
- Image sensor
The image sensor is a special camera for detecting light sources.
The image sensor transmits images to the control unit for the main-beam assistant.
The images are carried by an LVDS data line (LVDS: Low Voltage Differential Signalling).
The control unit for the main-beam assistant analyses the images.
The image sensor and the control unit are installed in a common housing and can only be supplied as a unit.
- Reverse gear switch
The main-beam headlights are not switched on if reverse gear is engaged.
In a manual-shift car, the reverse gear switch supplies the "reverse gear engaged" information.
The reverse gear switch sends this information to the light module.
- Selector lever position switch
The main-beam headlights are not switched on if reverse gear is engaged.
In a car fitted with electronic transmission control (EGS), the selector lever position switch supplies the "reverse gear engaged" information. The selector lever position switch sends this information to the EGS control unit. The EGS control unit sends this information to the light module or footwell module.
- Selector angle sensor and shift travel sensor
- E60, E61, E63, E64, E65, E66
The main-beam headlights are not switched on if reverse gear is engaged.
In a car fitted with sequential manual transmission (SMG), the selector angle sensor and the shift travel sensor supply the "reverse gear engaged" information. The selector angle sensor and the shift travel sensor send the information to the SMG control unit. The SMG control unit sends the information to the light module.
The following control units are involved in the main-beam assistant system:
- FLA: Main-beam assistant
The FLA control unit analyses the images from the image sensor. The FLA control unit receives information on road speed and yaw rate from the DSC control unit.
The FLA control unit sends a switch-on recommendation or a switch-off recommendation for the main-beam headlights to the light module. The recommendation depends on the traffic situation, the ambient light, and the car's road speed.
The FLA control unit is connected to the K-CAN.
- LM: Light module
- E60, E61, E63, E64, E65, E66
The light module receives various input variables for the main-beam headlights:
- Switch-on or switch-off recommendation from the FLA control unit
- Switch position of the light switch
- Switch position of the direction indicator/mean-beam switch
- Information from the reverse gear switch or the selector lever position switch or the selection angle and shift travel sensor
- Information from the rain-light sensor, as to whether the dipped headlights have to be switched on
On the basis of the input variables, the light module decides whether the main-beam headlights should be switched on or off.
- The light module actuates the bi-xenon headlights.
- The light module actuates the FLA indicator light in the instrument cluster.
A Check-Control symbol appears if the main-beam assistant fails.
The light module is connected to the K-CAN.
- FRM: Footwell module
- E90, E91, E92, E93, E70
The footwell module receives various input variables for the main-beam headlights:
- Switch-on or switch-off recommendation from the FLA control unit
- Switch position of the light switch
- Switch position of the direction indicator/mean-beam switch
- Information from the reverse gear switch or selector lever position switch
- Information from the rain-light sensor, as to whether the dipped headlights have to be switched on
On the basis of the input variables, the footwell module decides whether the main-beam headlights should be switched on or off.
- The footwell module actuates the bi-xenon headlights.
- The footwell module actuates the FLA indicator light in the instrument cluster.
A Check-Control symbol appears if the main-beam assistant fails.
The footwell module is connected to the K-CAN.
- DSC: Dynamic Stability Control
The DSC control unit calculates the car's road speed using the signals from the wheel-speed sensors. The DSC control unit sends the information on road speed to the main-beam assistant.
The DSC control unit also sends the information from the yaw-rate sensor in the DSC sensor to the main-beam assistant.
- EGS or SMG: Electronic gearbox control or sequential manual transmission
The EGS control unit receives the "Reverse gear engaged" information from the selector lever position switch. The EGS control unit is connected to the PT-CAN.
The SMG control unit receives the "Reverse gear engaged" information from the selector angle sensor and the shift travel sensor. The SMG control unit is connected to the PT-CAN.
- SZL: Steering Column Switch
The switch signals from the turn-signal/main-beam switch are picked up and evaluated by the SZL control unit. The SZL control unit sends the position of the turn-signal/main-beam switch to the light module (E60, E61, E63, E64, E65, E66) or footwell module (E90, E91, E92, E93, E70)
The following components are controlled:
- Bi-xenon headlights
The bi-xenon headlights are actuated by the light module.
If a main-beam assistant is fitted, only the main beam of the bi-xenon headlights are switched on. The halogen headlights are switched on only when the headlight flasher is actuated. In countries in which daytime driving lights are required by law, the halogen headlights are used for the daytime driving lights.
- Instrument cluster
The indicators in the instrument cluster are as follows:
- Main-beam indicator lamp (legally stipulated, blue)
- FLA indicator light
- Orange on BMW 3, 5 and 6-Series and on X5
- Blue on BMW 7-Series
- Check-Control symbol for failure of the main-beam assistant (yellow)
See the section entitled "SYSTEM FUNCTIONS " below.
The following components provide the power supply for the main-beam assistant:
- PM: Power module
- E65, E66
In the BMW 7-Series, the power module supplies power to the main-beam assistant.
- Rear power distributor
- E60, E61, E63, E64
In the BMW 5-Series and 6-Series, the rear power distributor supplies power to the main-beam assistant.
- Power distributor in junction box
- E90, E91, E92, E93
On the BMW 3-Series, the power distributor in the junction box supplies voltage to the main-beam assistant.
- Rear power distributor
- E70
On the BMW X5, the rear power distributor provides power to the main-beam assistant.