Audi A8 2019 Service Training page 79

Crash function in the low relative speed range
If the Airbag Control Module J234 detects a head-on colli-
sion at a low relative speed
deceleration, it decides situationally on the basis of its
algorithm whether to initiate electrical full tensioning.
Pre sense rear
With Audi pre sense rear, the following actions can be
initiated:
› RECAS alert (Rear End Collision Avoidance System).
› The electrical upper backrests move into an upright
position.
› The electrical head restraints move into an elevated
position.
› Inflation of the side bolsters in the seats and back-
rests.
› Closing the panoramic sunroof.
› Closing of the side windows apart from a residual gap.
› Speed-dependent partial or full tensioning of the
electrically reversible seat belt tensioners.
› Display of corrective action by Audi pre sense in the
instrument cluster.
Installation location
Audi pre sense rear is only possible if the vehicle has
Audi side assist. Audi side assist utilizes two "mid-range"
radar sensors which are able to detect objects within a
distance of about 0 - 76.5 yd (0 - 70 m) behind the vehicle.
Lane Change Assistance Control Module J769 is installed in
the rear bumper on the right-hand side of the vehicle. Lane
Change Assistance Control Module 2 J770 is installed in the
rear bumper on the left-hand side of the vehicle. Each
control module combines with a radar sensor to form a unit.
Audi pre sense rear utilizes the control modules including
the radar sensors of Audi side assist.
The relative speed is the difference in speed between one's own vehicle and the other vehicle involved in the collision.
1)
and at a low rate of vehicle
1)
Lane Change Assistance
Control Module 2
J770
Lane Change Assistance Control Module J769
is installed similarly on the right-hand side of the vehicle.
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A condition is that no pyrotechnic components, such as the
airbags, deploy during these head-on collisions. In addition
to this, the closing of the side windows and the panoramic
sunroof as well as the inflation of the seat and backrest
side bolsters are initiated at speeds of 31.0 mph (50 km/h)
or higher.
Overview of the radar sensors
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