Audi R8 2008 Service Training Manual page 17

Data Transfer
Airbag Control Module J234 is a member of the
Powertrain CAN-bus.
J234 relays information over the Powertrain CAN-bus:
– Activation of Airbag Malfunction Indicator Lamp K75.
– Activation of the Safety Belt Warning System.
– Diagnostic Data.
– Crash Signal.
– ESP Data.
– Passenger's Front Airbag Active / Inactive Status.
J234 evaluates the following information from the data
bus:
– Dimming for the Passenger's Airbag Disabled
Indicator Lamp.
The information that a crash has occurred is transmitted
on the CAN-bus to other control modules to unlock the
vehicle doors, shut OFF the fuel pump, and activate the
emergency flasher system.
Occupant Protection
Airbag Malfunction Indicator
Lamp K75
K75 is located in Instrument Cluster Control Module J285
and is illuminated via the CAN-bus.
Rear Impact Recognition
During a rear impact collision, the vehicle is strongly
accelerated in the driving direction.
Crash sensors in J234 and Crash Sensors G283 and G284
recognize this vehicle acceleration and send their signals
to J234.
If the signals exceed a specified value, the pyrotechnic
safety belt tensioners the battery interrupt igniter are
activated.
Reference
For more information about the
Occupant Protection System, refer to
the 2008 Audi TT Vehicle Introduction,
Self Study Program 99703.
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