3 Series E46 316i (M43TU) SAL
At speeds upwards of 50 km/h, the signals from the yaw-rate sensor (in the DSC sensor) form the primary
basis for control of the adaptive headlights function.
Reason: For a constant cornering radius, the steering angle required increases disproportionately with
speed. In addition, the steering angle required also depends on the coefficient of friction of the road
surface.
The yaw rate is directly proportional to speed. For this reason, the yaw rate is always the most suitable
measure for controlling the adaptive headlights at high speeds.
Even at high speeds, however, the steering angle sensor signal is used to detect (predict) the driver's
commands in advance. This prediction is important: The yaw rate signal is not supplied until the vehicle
has responded to the steering wheel movement.
The steering-angle sensor signal is disabled so that rapid, momentary steering adjustments do not affect
the adaptive headlights function.
A number of control units are involved in the adaptive headlights system (see above: GM, EGS, KOMBI).
Depending on the series and model concerned, the adaptive headlights are actuated by the following control units:
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AHL control unit
> E46/2, E46/C, E53 and E83 until 09/2006
The AHL control unit controls the adaptive headlights.
For safety reasons, the AHL control unit is also responsible for the automatic headlight-range adjustment. This is
because: Oncoming traffic must not be dazzled by the adaptive headlights. If a headlight sticks in an
unfavourable position, the AHL control unit will attempt to move this headlight down (using the stepper motors in
the automatic headlight-range adjustment).
The AHL control unit is connected to the K-bus and the PT-CAN.
[more ...]
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LM: Light module
> E83 from 09/2006
The AHL control unit is integrated in the light module.
The light module controls and monitors all vehicle lights. Information is received and transmitted over the data
buses PT-CAN, LIN bus and K-bus.
[more ...]
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Stepper motor controllers
The stepper motor controllers (SMC) control the stepper motors in the headlights (for the automatic headlight-
range adjustment and for the adaptive headlights).
[more ...]
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LSZ: Light switch cluster
> E46/2, E46/C, E53 and E83 until 09/2006 (E53: light module)
The light switch cluster forwards the prompts from the light switch and from the turn-signal/main-beam switch to
the AHL control unit (via the K-bus).
[more ...]
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Xenon-headlight control unit
The xenon-headlight control unit actuates the bulb in the bi-xenon headlights.
[more ...]
The following components are controlled:
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Stepper motors for the adaptive headlights
The stepper motors turn the positioner modules in the bi-xenon headlights.
The stepper motors swivel the headlights along the vertical and horizontal axes. (vertical = up and down for the
SBT Adaptive headlights E46/2, E46/C, E53, E83
BMW AG - TIS
19.01.2013 20:58
Issue status (12/2007) Valid only until next DVD is issued
Copyright
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