Mercedes-Benz S-Class 2019 Operator's Manual page 211

If the system reaches a system limitation or the
driver has not steered the vehicle for a consider‐
able period of time or has removed their hands
from the steering wheel, the system will,
depending on the situation, first alert the driver
with a visual warning. Display
multifunction display. If the driver still does not
steer the vehicle, or has still not taken hold of
the steering wheel, a repeated warning tone
sounds in addition to the visual warning mes‐
sage to remind the driver to take control of the
vehicle.
The warning message does not appear or disap‐
pears if one of the following conditions are met:
The driver steers the vehicle.
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The driver presses a steering wheel button or
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operates Touch Control.
Active Steering Assist is only an aid. The driver is
responsible for the distance to the vehicle in
front, for vehicle speed, for braking in good time
and for staying in lane. Before changing lanes,
the driver must make sure that the neighboring
lane is free (glance over the shoulder).
System limitations
Active Steering Assist has a limited steering tor‐
que for lateral guidance. In some cases, the
steering intervention is not sufficient to keep the
vehicle in the lane.
If the detection of lane markings and vehicles
1 appears in the
ahead is impaired, Active Steering Assist
switches to passive mode. The system provides
no support in this case. During the transition
from the active to passive status, the è sym‐
bol is shown as enlarged and flashes yellow.
Once the system is passive the è symbol is
grayed out in the multifunction display.
Driving and parking 209
The system may be impaired or may not function
in the following instances:
In snow, rain, fog, heavy spray, if there is
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glare, direct sunlight, greatly varying ambient
light, reflections or strong shadows on the
roadway.
Insufficient road illumination.
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The windshield in the area of the camera is
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dirty, fogged up, damaged or covered.
Absence of lane markings, or several unclear
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lane markings, or if the markings change rap‐
idly.
The distance to the vehicle in front is too
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small and the lane markings thus cannot be
detected.
The road is narrow and winding.
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Obstacles on the lane or projecting out into
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the lane.
The system does not provide assistance in the
following conditions:
On tight bends, traffic circles and when turn‐
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ing.