Airbag Control Unit J234 - Audi A3 Sportback 332 Service

Occupant protection

Airbag control unit J234

The airbag control unit's hardware and electronics have been modified compared to the control unit in the
Audi A3 3-door such that they are also capable of activating the dual-stage front airbags. The airbag control
unit has also been modified in such a way that no mechanical safing sensor is required.
The airbag control unit is integrated in the drive train CAN bus.
The airbag electronics basically have the following
tasks:
– collision detection (front, side, rear)
– defined deployment of the airbags or front
airbag stages, belt tensioners and battery
disconnector
– activation of the belt-on indicator
– evaluation of all input information
– continuous monitoring of the entire airbag
system
– capacitor-based independent power supply for
a defined period of time
(approx. 150 ms)
– fault display by failure warning lamp
– storage of fault/ and
collision information
– notification of a collision event to other system
components via the drive train CAN-bus or
a discrete collision output (conventionally wired)
Information about the occurrence of a crash is
utilised by other control units for opening the
central locking system, shutting off the fuel supply
and activating the hazard warning light system, etc.
Rear collision detection
If the airbag control unit recognises a rear collision whose severity exceeds the predefined deployment
threshold, then it ignites the belt tensioners and, where fitted, the battery isolation igniter.
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