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The system comprises driver/passenger air-
bags, front side airbags, optional rear side
airbags, SIDEGUARDS
®
, three point front seat
belts with ball tensioners and belt force limit-
ers, three point rear outer seat belts, centre
lap belt (for fixed rear seat bench), Isofix pre-
paration in rear of vehicle, and a total of 6
non-central accelerometers:
– 2 front impact crash sensors
– 2 driver/passenger side airbag crash sen-
sors, (in the B-pillar for side impact)
– 2 driver/passenger rear side airbag crash
sensors, (on the C-pillar for side impact) To complement the comprehensive body
modifications, occupant protection has been
improved through the further development of
the familiar 8.4 airbag system.
The new generation bears the designa-
tion 8.4 E, where the E stands for
"extended".
The position of the sensors is selected so that
they are installed as near as possible to the
outer structure of the vehicle.
This enables quicker deceleration detection in
the event of an impact.The external sensors deliver digitised acceler-
ation data to the airbag control unit, which is
then evaluated in the control unit and which
triggers the relevant restraint system compo-
nents.
Key
E224 Key switch for switching off
passenger’s side airbag
G179 Side airbag crash sensor, driver’s
side (B-pillar)
G180 Side airbag crash sensor, passenger’s
side (B-pillar)
G256 Crash sensor for rear side airbag,
driver’s side
G257 Crash sensor for rear side airbag,
passenger's side
G283 Front airbag crash sensor, driver’s
side
G284 Front airbag crash sensor,
passenger’s side
J162 Heater control unit
J220 Control unit for motronic
J234 Airbag control unit
J285 Control unit with display unit in
dash panel insert
J393 Central control unit for convenience
system
J526 Control unit for telephone /
telematics
J533 Diagnosis interface for data bus
(Gateway)K75 Airbag warning lamp
K145 "Airbag off" warning lamp,
passenger's side
N95 Airbag igniter, driver's side
N131 Airbag igniter 1, passenger's side
N153 Igniter for belt tensioner, driver's side
N154 Igniter for belt tensioner,
passenger's side
N199 Igniter for side airbag, driver’s side
N200 Igniter for side airbag, passenger's
side
N201 Igniter for rear side airbag,
driver’s side
N202 Igniter for rear side airbag,
passenger's side
N277 Igniter for airbag in B-pillar
(SIDEGUARD
®
), driver's side
N278 Igniter for airbag in B-pillar
(SIDEGUARD
®
), passenger's side
T16 Connector, 16-pin, diagnosis
connection
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14
Crash sensors for front airbag G283, 284
Both sensors for front impact detection func-
tion in conjunction with the crash sensor and
the safe sensor which are integrated into the
airbag control unit J234.
Deceleration load
Time [ms]
Vehicle rebound Impact
Triggering of belt tensioners
Triggering of front airbags
Front airbags inflated
Belt force limiter
response
Damping function
response in
the steering column
SSP254_063
SSP254_064
Upper body
Head
If a certain signal threshold is exceeded in the
front airbag crash sensor, a threshold reduc-
tion is activated in the airbag control unit,
which results in a shorter triggering time.
Occupant protection
SSP254_058
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Re-encoding of the airbag control unit is no
longer possible after the first crash data mes-
sage is stored.
Triggering is performed in two thresholds
depending upon the deceleration value:
– Threshold 1 = belt tensioners only
– Threshold 2 = belt tensioners and airbag(s)
Crash sensors for side airbags
G179, 180, 256, 257
In order to trigger the components of the
restraint system, two simultaneous impact
detection signals are required for the plausi-
bility check:
– from both opposing crash sensors
(B-pillar left with right and/or
(C-pillar left with right) and
– from the control unit internal crash sen-
sors.
The crash sensors are designed in such a way
that incorrect installation is excluded.
Airbag control unit J234
The warning lamp for airbag K75 is activated
continuously following a detected impact.
"CRASH DATA STORED" and the triggered
components are displayed with fault code
during fault memory readout.
Sensors and components to be replaced
following an accident, are listed in the
current workshop manual.
SSP254_059
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16
Occupant protection
Front belt attachment
Belt lock and strap fastenings are perma-
nently connected to the seat frame. Thus, in
conjunction with the seat belt height adjuster,
an optimal belt fitting can be achieved for
each seat position.
Deactivation of passenger airbag
Deactivation of the passenger airbag is only
possible via the key switch. In the Audi A4, the
passenger's side airbag is also deactivated.
Deactivation via the diagnostic tester is not
possible.
If a customer requires the deactivation func-
tion where a key switch is not fitted, this can
only be achieved by retrofitting the key switch
and airbag OFF lamp and by re-encoding of
the airbag control unit.
Front head restraints
In order to offer a high degree of occupant
protection in conjunction with the seat belt
and airbag, the front head restraints have
been supplemented by an integral locking
mechanism.
aa
aaa
a
SSP254_011
SSP254_102SSP254_101
