Audi A8 2019 Service Training page 70

Installation location
The lap belt tensioner is engaged and bolted to the rear
bulkhead at the rear left and right.
Coupling
The seat belt is diverted at the seat belt end fitting in the
seat frame area and, unlike in other vehicles, is movable
without lap belt tensioners. A coupling is stitched to the
end of the seat belt. The lap belt tensioner coupling is
inserted into the seat belt coupling and clipped into place.
Diagnostics
The lap belt tensioner is a pyrotechnic component. The
safety instructions are the same as for other pyrotechnic
components. The lap belt tensioner becomes unusable
after its pyrotechnic charge has ignited and has to be
replaced as a unit. Airbag Control Module J234 continu-
ously monitors the lap belt tensioners for proper function-
ing. Faults in the system are registered as DTCs by J234.
These faults can be cleared using "Guided Fault Finding".
Reference
The basic working principle of a lap belt tensioner is explained in eSelf-Study Program
66
990143, The 2015 Audi A3 Introduction.
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