BMW 7 Series: Headlight Driver Module

The headlight driver module controls and monitors the stepper motors for the adaptive headlights and the headlight beam throw adjustment system of the respective bi-xenon headlight.

The integrated chassis management makes available the values for the dynamic headlight beam throw adjustment system to the footwell module. The footwell module receives these values via the K-CAN2. In this way the beam angle can be adapted to the different driving situations, e.g. laden/unladen.

The signal from the integrated chassis management must be transferred to the KCAN2 in the central gateway module.

Fig. 60: Headlight Driver Module Circuit

COMPONENTS DESCRIPTION CHART

1. Stepper motor for adaptive headlight
2. Headlight driver module
3. Stepper motor, headlight vertical aim control
4. Zero position sensor
5. LIN-Bus
6. Coding pin for right/left
7. Voltage supply +

The headlight driver module fulfils the following functions:

• Receiving and evaluating the data sent from the footwell module via the LIN-bus:
  • Reference run
  • Target position commands
  • Diagnosis requests
• Output control of the stepper motors
• Zero position acquisition of swivel module
• Reference run of swivel module
• Position feedback of swivel module to footwell module
• Diagnosis
• Feedback of diagnosis data to the footwell module.

The footwell module in its function as the central control unit for the adaptive headlight checks the status of the headlight driver modules every 20 ms.

Furthermore, the footwell module initiates activation of the LEDs in the front headlights.

Zero Position of Swivel Module

The zero position of the swivel module is determined by the zero position sensor. The zero position sensor is a Hall sensor. The falling edge of the Hall sensor is evaluated to determine the zero position. The zero position corresponds to exactly the position of the swivel module in the straight-ahead position of the vehicle.

The headlight driver modules prepare the data for data transfer via the LIN bus. The footwell module requests the data from the headlight driver modules.

NOTE: The sensor signal can be read out during diagnosis.

The sensor is defective if no sensor signal is applied.

Switch-off Conditions

As from "Terminal 15 OFF", the footwell module sends the request via the LIN bus to assume the rest position of both swivel modules to the headlight driver modules. On reaching the rest position of the swivel modules, the headlight driver modules send a confirmation to the footwell module. The headlight driver modules also activate the side lights function.

Afterunning Time

The afterunning time is 2 seconds.

Check Control Message

The Check Control messages below exist for the adaptive headlights and the beam throw adjustment system.

CHECK CONTROL MESSAGE CHART

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