11
Activation of the electrically reversible seat belt tensioners
If corrective adjustments are made by Audipresense, the
airbagcontrol unit J234 initiates tensioning of the electrically
reversible seat belt tensioners via the front left seat belt tensioner
control unit J854 and the front right seat belt tensioner control
unit J855. Seat belt tensioners J854 and J855 are connected to the
airbag control unit via a sub-bus system. Refer to page18 for further
information about Audipresense and to page12 for further infor-
mation about the reversible seat belt tensioners.
637_008
637_018
Terminal 30
Diagnostics
The airbagcontrol unit J234 is a terminal 30 control unit and is
discretely connected to terminal 30 and terminal 15. It addition-
ally receives digital information on the status of terminal 15 via
the data bus diagnostic interface J533 (gateway). The airbag
system is only deploys when the ignition is on (terminal 15 on).
A capacitor is integrated in the control unit J234. If terminals 15
and 30 are disconnected, this capacitor enables the dierent
pyrotechnic components (e.g. airbags, seat belt tensioners) to
deploy. If only terminal 15 is disconnected, the control unit is still
supplied by terminal 30 (continuous pulse). This allows the various
pyrotechnic components to be initiated by the vehicle battery,
making even longer deployment times possible.
The diagnostic address of the airbagcontrol unit J234 is
"15–Airbag". The generation of control units (system designation)
is "Airbag10.44" and can be retrieved in the Guided Fault Finding
under "Control unit identification".
Since the installed position of the airbagcontrol unit J234 can have
tolerances, the inertial sensors can be calibrated in order to
measure acceleration in the X and Y directions and the yaw rate
about the Z axis.
If a new airbagcontrol unit J234 has been installed but the basic
setting procedure has not yet been carried out, the event
"C115E54 - inertial sensors - no basic setting" is entered into the
fault memory.
During subsequent work basic setting of the inertial sensors of
airbag control unit J234 must be carried out using the Guided Fault
Finding function.
• If control unit J234 was removed and installed.
• If control unit J234 is replaced.
Key:
A Battery
J234 Airbag control unit
J367 Battery monitor control unit
J519 Onboard power supply control unit
J533 Data bus diagnostic interface
Data bus
diagnostic interface
J533
Airbag control unit
J234
Control unit for
front left seat belt
tensioner
J854
Seat occupancy
recognition control unit
J706
Control unit for
front right seat belt
tensioner
J855
Extract from the topology
Function diagram
LIN bus
FlexRay
LIN bus
FlexRay
Sub-bus
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