1 Series E87 118d (M47T2) 5-door
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Zero-position sensor
> E63, E64
> E70, E81, E87, E90, E91, E92, E93
Automotive Lighting headlights, previously Bosch, have a zero-position sensor.
The zero-position sensor registers the horizontal movement of the headlight.
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EGS control unit or reversing light switch
When reverse gear is engaged, the headlights are moved to the straight-ahead position.
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On vehicles with automatic transmission, the EGS control unit provides the "Reverse gear engaged" signal.
(EGS: electronic transmission control).
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On vehicles with manual transmission, the signal is supplied by the reversing light switch.
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Rain-light sensor for automatic driving lights control
The rain-light sensor measures the ambient brightness outside the vehicle.
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In twilight conditions, the rain-light sensor transmits the message "Twilight" so that the
automatic headlight-range adjustment can activate dipped headlights. The headlights are tilted up and
down as required, but they are not yet moved towards the bend in the road.
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In darkness, the rain-light sensor sends the message "Darkness". The adaptive headlights are then
activated when the vehicle is cornering. The headlights are moved to the left or right:
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Steering-angle sensor and DSC sensor
The steering angle sensor and DSC sensor (DSC = Dynamic Stability Control) supply signals for the
adaptive headlights to the adaptive headlights control unit. These signals are evaluated as follows, depending
on the vehicle's speed:
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Vehicle speeds up to 30 km/h:
The adaptive headlights function is controlled using the information from the steering angle sensor (in the
steering column switch cluster).
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Vehicle speeds between 30 km/h and 50 km/h
:
In the 30 to 50 km/h speed range, there is a
continuous transition in signal evaluation: from the
evaluation of signals sent by the steering angle sensor to evaluation of the signals sent by the yaw-rate
sensor (in the DSC sensor).
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In extreme dynamic driving situations, e.g. if the vehicle starts to skid or fishtail, even at speeds less
than 50 km/h , the signals from the yaw-rate-sensor are considered.
If the vehicle starts to skid or fishtail, the headlights will move to the straight-ahead position. The headlights
are not moved until the vehicle has stabilised.
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Vehicle speeds over 50 km/h:
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.
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
SBT Adaptive headlights E60, E61, E63, E64, E65, E66, E70, E81, E87, E90, E91, E92,
BMW AG - TIS
18.01.2013 18:46
Issue status (12/2007) Valid only until next DVD is issued
Copyright
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