2001 AUDI A4 engine

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9
Side impact design features
In the floor area, the cell consists of three
large tailored blanks, which ensure a stable
connection between the front and rear of the
vehicle.
Weight-saving optimisation of deformation
characteristics in the event of a side impact
was achieved by the use of an aluminium
extruded profile in the sill.
“tailored blanks” are made-to-measure
sheet metal parts with varying material
thickness.

SSP254_055
SSP254_056

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10
Body
Doors
The doors of the Audi A4 demonstrate a sig-
nificantly increased rigidity due to the one-
piece door shell construction.
For the first time, a so-called spray-on noise
insulation is used, which is sprayed on as
required and allows weight reduction for the
same effectiveness.
The newly developed sub-frame is bolted to
the door shell via fitted bolts.
In addition, the doors have been fitted with a
second weatherseal. One weatherseal is fitted
to the door and the other is fitted to the body.
The new door concept permits a reduction in
the overall noise level of a further 3 dB (A) and
thus contributes to improving the aero-acous-
tics.
SSP254_066
SSP254_075SSP254_067
Noise insulation
Roof trim strip
Door window
seal
Door windo
w
Door frameDoor frame seal
Door trim
Door sealRoof

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11
Luggage compartment lid
The luggage compartment lid should always
be operated via the radio remote control.
The lock cylinder for the luggage compart-
ment lid is integrated into the handle.
Emergency door locking
In the event of failure of the central locking,
e.g. due to power supply faults, each door can
be individually locked without using the lock
cylinder.
Firstly, with the door open, the cap must be
removed. Emergency locking is effected by
inserting the ignition key.
After the door has been closed, it is not possi-
ble to open it from the outside.
The door can be opened from the inside by
actuating the door release handle twice.
Continuous locking of luggage compartment
If the lock cylinder is in the horizontal posi-
tion with the key removed, the luggage com-
partment lid is no longer included in the
central locking system. Opening is then only
possible via the centre unlocking button of
the radio remote control.
When the lock cylinder is in the vertical posi-
tion, the lid is an integral part of the central
locking system.
Manual unlocking and opening
is effected by turning the key to the left.
In this position, it is not possible to remove
the key, which must subsequently be returned
to the vertical position.
Thus, it is ensured that the luggage compart-
ment lid is an integral part of the central lock-
ing system.
SSP254_069
SSP254_070
SSP254_071
SSP254_072

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12
Occupant protection
Overview of system
G 256 N277G179G180
N153
K145
AIRBAGOFF
N95
N202
N154
N278
G 257
J533
N199
N201
J234
G 283G 284
E224
AUSEIN
AIRBAG
N131
N200
J393J526 T16
J220
J162
J285/K75

SSP254_029

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13
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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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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15
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