2008 AUDI A4 AVANT ABS

-Airbag system
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& WARNING
Never rely on airbags alone for protection.
• Even when they deploy, airbags provide only supplemental
protection .
• Airbag work most effectively when used with properly worn
safety belts.
• Therefore, always wear your safety belts and make sure that
everybody in your vehicle is properly restrained.
& WARNING
A person on the front passenger seat, especially infants and small children, will receive serious injuries and can even be killed by
being too close to the airbag when it inflates.
• Although the Advanced Airbag System in your vehicle is
designed to turn off the front passenger airbag if an infant or a
small child is on the front passenger seat, nobody can absolutely
guarantee that deployment under these special conditions is
impossible in all conceivable situations that may happen during
the useful life of your vehicle.
• The Advanced Airbag System will deploy in accordance with
the
"low risk" option under the U.S. Federal Standard if a child that
is heavier than the typical one-year old child is on the front
passenger seat and the other conditions for airbag deployment
are met.
• Accident statistics have shown that children are generally safer
in the rear seat area than in the front seating position.
• For their own safety, all children, especially 12 years and
younger, should always ride in the back properly restrained for
their age and size.
•
Advanced front airbag system
Your vehicle is equipped with a front Advanced Airbag System in compliance with United States Federal Motor Vehicle Safety Stan­
dard 208 as applicable at the time your vehicle was manufactured .
The front Advanced Airbag System supplements the safety belts to
provide additional protection for the driver's and front passenger's
heads and upper bodies in frontal crashes. The airbags inflate only
in frontal impacts when the vehicle deceleration is high enough.
The front Advanced Airbag System for the front seat occupants is
not a substitute for your safety belts. Rather, it is part of the overall
occupant restraint system in your vehicle . Always remember that
the airbag system can only help to protect you, if you are sitting
upright, wearing your safety belt and wearing it properly. This is why
you and your passengers must always be properly restrained, not
just because the law requires you to be.
The Advanced Airbag System in your vehicle has been certified to
meet the "low risk" requirements for 3 and 6 year-old children on the
passenger side and very small adults on the driver side. The low risk
deployment criteria are intended to help reduce the risk of injury
through interaction with the front airbag that can occur, for example, by being too close to the steering wheel and instrument
panel when the airbag inflates .
In addition, the system has been certified to comply with the
"suppression" requirements of the Safety Standard, to turn off the
front airbag for infants 12 months old and younger who are
restrained on the front passenger seat in child restraints that are
listed in the
Standard~ page 272 .
"Suppression" requires the front airbag on the passenger side to be
turned off if:
• a child up to about one year of age is restrained on the front
passenger seat in one of the rear-facing or forward-facing infant
restraints listed in Federal Motor Vehicle Safety Standard 208 with
which the Advanced Airbag System in your vehicle was certified. For
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-Airbag system ---=--.:..,.._ _________________________________ _
&, WARNING (continued )
cellular telephones and CB radios, etc .) must be performed by a
qualified technician who has the training and special equipment
necessary .
• For any work on the airbag system , we strongly recommend
that you see your authorized Audi dealer or qualified workshop .
• Never modify the front bumper or parts of the vehicle body .
• Always make sure that the side airbag can inflate without inter ­
ference :
- Never install seat covers or replacement upholstery over the
front seatba cks that have not been specifically approved by
Audi.
- Never use additional seat cushions that cover the areas
where the side airbags inflate.
- Damage to the original seat covers or to the seam in the area
of the side airbag module must always be repaired immedi­
ately by an authorized Audi dealer .
• The airbag system can be activated only once. After an airbag
has inflated , it must be replaced by an authorized Audi dealer or
qualified technician who has the technical information , training
and special equipment necessary.
• The airbag system can be deployed only once. After an airbag
has been deployed, it must be replaced with new replacement
parts designed and approved especially for your Audi model
version. Replacement of complete airbag systems or airbag
components must be performed by qualified workshops only .
Make sure that any a irbag service action is entered in your Audi
Maintenance
& Warranty booklet under AIRBAG REPLACEMENT
RECORD .
• In accidents when an airbag is deployed, the vehicle battery
separates the alternator and the starter from the vehi cle electrical
system for safety reasons with a pyrotechnic circuit interrupter.
-Work on the pyrotechni c circuit interrupter must only be
performed by a qualified dealer -risk of an accident !
&, WARNING (continued )
-If the vehicle or the circuit interrupter is scrapped, all appli­
cable safety precautions must be followed.
•
Other things that can affect Advanced Airbag performance
Changing the vehic le 's suspension system can change the way that
t he A dvance d Ai rbag S ystem p erf o rm s in a c rash. F or example,
using tire -rim combinations not approved by Audi, lowerin g the
ve hicle , ch ang ing the stiff ness of the suspe nsion, includ ing the
springs, suspension struts, shock absorbers etc. can chang e the
fo rces that a re measured by the airbag senso rs and se nt to the elec­
tronic control u nit. Some suspension chan ges can, for exampl e,
i n crease the fo rce level s measured by the sen so rs and ma ke the
a irbag s yste m de plo y in cras he s in w hi ch it wou ld not de ploy if th e
changes had not been made. Other kinds of changes may reduce
t h e fo rce lev els measu red by the senso rs a nd p reven t the airb ag
from dep loying when it should.
T he sens ors i n the safe ty belt buckle f or the dri ve r and front
passeng er seat tell t he electronic contro l modu le if the safety belt is
la tched o r not. If t he sa fe ty bel t i s being used, the fro nt ai rbag wi ll
deploy at a s ligh tly high er rate o f veh icle dece lerat io n th an if th e
safety be lt is not being u sed . Th erefo re , in a particula r co llision, it is
poss ib le th at a n airbag will not deplo y at a seat ing po sit io n wh ere
the safety be lt is being used but wi ll inflate at the pos ition where the
safety be lt is not bei ng used . It is im po rta nt tha t noth ing i nte rfere
with the safety belt buc kles so that the sensors can send the correct
i nf orm atio n abou t s afe ty belt use to th e electr onic co ntrol uni t.
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Children who weigh more than about 80 lbs (36 kg) and are at least
4 ft . 9 in. tal l can genera lly use the veh ic le's three po int lap a nd
shou lder belts . Chi ldren should use a lap belt only in very excep ­
tiona l situations and on ly if no child restraint system for the child's
size and weight or safer a lternative means of transportation of the
child is available. In these exceptiona l situations, the use of a lap
belt is better t han permitting t he ch ild to re main total ly unre ­
strained. But remember : a lap be lt cannot provide the same level of
protection as a proper c hild restraint or a t hree -poi nt lap and
shou lder be lt if the child is big enough . A lso, using a lap belt for
younger chi ldre n, who s hould be us ing a chi ld restrai nt, may v iola te
l aws in your state or Province .
N ever use a lap belt alone to rest ra in a chi ld that we ig hs less than
about 80 lbs (36 kg) and w ho is less t han 4'9" ta ll. A lways remember
t hat chi ld ren do not have the pronounced pelv ic structure requ ired
f or t he proper function o f lap belts . If a lap belt is o nly restra int
system available, then the chi ld's safety absolutely requires that the
l ap be lt be fastened snug ly and as low as possible around t he pelv is
l et a lap belt pass over the chi ld's stomach or abdomen .
& WARNING
Using wrong child restraints or improperly installed child
restraints can cau se seriou s personal injury or death in a crash.
• Failure to properly route safety belt s over a child's body will
cau se severe injurie s in a crash . The lap belt portion of the three
point belt a s well as any lap belt alone must always pass as low as
po ssible acros s the pelvis, never over the stomach or abdomen.
• An improperly worn safety belt will not provide the best protec­
tion in a crash and may cause serious personal injury . Al ways
make sure that children and other vehicle occupants properly
wear available restraint sy stem s. Carefully follow the in struction s
prov ided by the manufacturers of child restraints .
•
Installing a child safety seat
Securing a child safety seat using a safety
belt
S afe ty belts for the rea r seats and the fr ont pa ssenger can
be locke d with the c onvertible locking retract or to prop ­
erly secure child safety seats.
T he safe ty belts emergency locking re tracto rs fo r the rea r sea ts
sa fety be lts a nd for t he front passenger's seat safety belt have a
conve rtible lock ing ret ractor for child rest ra ints . The safety belt
must be loc ked so t hat belt webbing ca nnot unree l. The retractor
can be activated to lock the safety be lt and prevent the safety be lt
webbi ng from l oosen ing up dur ing normal dr ivi ng. A c hild sa fe ty
seat can only be properly instal led when the safety belt is locked so
t hat t he ch ild and c hild safety seat will s tay in place .
A lways remember: Even though your vehicle is equipped with an
Advanced Ai rbag sys tem, al l c h ild ren, especially those 12 years and
younger, should always r ide in the back seat proper ly restra ined for
their age and size.
& WARNING
Improperly installed child safety seats increase the risk of serious
per sonal injury and death in a collision .
• Always make sure that the safety belt retractor is locked when
installing a child safety seat. An unlo cked safety belt retra ctor
cannot hold the child safety seat in pla ce during normal driving or
in a crash.
• Alway s buckle the child safety seat firmly
in place even if a
c hild is not sitting in it. A loose child safety seat can fly around
during a sudden stop or in a collision
• Alway s make sure that the rear seat backre st to which the
center rear safety belt is attached is securely latched whenever
the rear center safety belt is being u sed to se cure a child re straint.
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Intelligent technology
Notice about data recorded by
vehicle control modules
Your vehicle is not equipped with an Event Data Recorder (EDR),
installed by some manufacturers for the express purpose of
capturing data for retrieval after an accident or crash event . EDR's
are sometimes called "crash recorders" .
Some state laws restrict the retrieval or downloading of data stored
by EDR's that were insta lled in a vehicle for the express purpose of
retrieving data after an accident or crash event without the owner's
consent.
Although your vehicle is not equipped with an EDR, it is equipped
with a number of electronic control modules for various vehicle
systems such as, for example, engine function, emission control, as
we ll
as for the airbags and safety belts.
These electronic control modules also record vehicle-related data
during normal vehicle operation for diagnostic and repair purposes .
The recording capacity of the electronic control modules is limited
to data (no sound is recorded) and only a small amount of data is
actually recorded over a very limited period of time and stored when
a system fault or other condition is sensed by a control unit. Some
of the data then stored may relate to vehic le speed, d irection,
braking as well as restraint system use and performance in the
event of a crash or other condition . Stored data can only be read and
down loaded with special equipment. •
Electronic Stabilization Program (ESP)
General information
The ESP improves the vehicle stability.
(X) CD
Fig. 199 Center
console with ESP
sw itch
ESP is designed to he lp you maintain vehic le control in situations
where the car approaches the limits of "grip", especial ly when
acce lerating and cornering. ESP reduces the risk of skidding and
improves stability under al l road conditions.
The system operates across the entire speed range in combination
with the ABS system . If the Anti-Lock Brake System (ABS) malfunc ­
t ions, the ESP will a lso shu t down.
How the system works
The Anti-Lock Brake System (ABS), Electronic Differential Lock (EDU
and the Anti -Slip Regu lation System (ASR) are integrated in the e lec ­
tronic stabilization program . In addition to the data provided by
these functions, the ESP control unit requires additional measure ­
ment data provided by high performance sensors. The rotational
.,,.

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speed of the vehicle about its vertica l axis, the lateral acce leration
ac ting on the veh ic le, the brake pressure and the s teering ang le a re
a ll measured .
The direction in which the driver wishes to travel is determined with
the aid of the steering angle and veh icle speed and is continua lly
compared with the actual behavior of the vehicle. If the two do not
match, -for example, when the vehicle starts hydrop la ning on a
wet road -
, ESP will au tomatical ly brake the appropria te wheel to
correct the problem .
The vehicle is then stabi lized by the forces acting on the whee l
during braking . If the vehicle is
oversteering (r ea r tends to skid out
of the turn), t he brakes are main ly app lied on the whee l that is on
the outside of the curve . In the case of a vehicle that is
understeering
(tendency to s lide out of the curve) , the bra kes are applied at the
rear whee l that is on the inside of the curve. An acoustic signal indi ­
cates when ESP brake appl ication cuts in
=> & .
The system operates across the entire speed range in combination
wi th the ABS system
~ page 240. If the Ant i- Lock Brake Sys te m
(ABS) malfunctions, the ESP wi ll be out of act ion as well.
Ac tivat ion
When you turn on the engine, ESP will automatica lly be activated
and will perfo rm a self -test.
You can activate a deactivated ESP or deact ivated ASR as requ ired
by pressing the
=> page 236, fig. 199 button.
D eac tiva tion
Norma lly, the ESP should always be on .
When necessary, you can deact ivate Anti -Slip Regulat ion (ASR) or
the Electronic Stabilization Program (ESP) by pressing the button
=> page 236, fig. 199 .
• Dea ctivating A SR: Tap briefly on the ESP button . In certain excep ­
t iona l situations (e .g. driving wit h tire chains or a t a forced pace
around a track), the Anti-S lip Regu lation (ASR) can be deactivated
Controls and equip­
ment Safety first Vehicle operation
=> page
238 . The ESP check light flashes . T ap the ESP button again
t o r eact ivate ASR. The ESP check light g oes out .
• Deactiv ating ESP : Press the ESP button for more than 3 seconds .
W ith ESP deactivated, the ESP check ligh t illum inates cons tant ly .
Press the ESP button again to reactivate ESP . The ESP check light
g o es out .
& WARNING
The Electronic Stabilization Program i s neve rthele ss subject to the
laws of physi cs . It is part icularly important to pa y attent ion to thi s
fact on we t and slippery roads . It is therefore important that you
always adapt your driving to the condit ion of the road and traffic
c onditions. Do not allow the inc reased safety provided by the Elec ­
tronic Stabiliz ation Program sy stem to lull you into a ccepting
additional safety ri sk s.
• Plea se note that when ESP or ASR is dea ctivated , the drive
wheels can spin on icy and slippery roads and the vehicle can
break a way -da nger of skidding! •
Electronic differential lock (EDL)
The elec tr o nic differen tial l ock mon itors t he r ota tion al
speed of the drive wheels .
Gener al not es
The elec tronic d if f erential l ock (EDU helps the ca r to start mov ing,
accelerate and c limb a grad ient on surfaces providing poor or
a lmost n o grip. W ithout EDL, th is w ould be difficult, if no t impos ­
sib le.
How the system works
The EDL operates automatical ly. It monitors the rotational speed of
the drive whee ls on an ax le with the he lp of t he ABS senso rs
=> page 2 40 . If a noticeable difference in rotational speed between
the drive wheels on one axle is de tected (e .g. on sl ippery grou nd
on .,,.
Vehicle care Do-it-yourself service Technical data

-Intelligent technology
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one side), the spinning wheel is braked, thereby transferring power
to the other drive wheel or wheels (all- wheel drivel. This is done up
to a speed of about 60 mph (100 km/h). Noises from the brake
system signal that wheel spin is being control led.
Driving off
When driving off, always be sure to keep road conditions in mind as
you accelerate. If one drive wheel spins because it is on a surface
with less grip, gradual ly increase the pressure on the accelerator
pedal until the car starts to move. The wheel less able to transfer
power spins.
Overheating of brakes
To prevent the disc brake of the braked wheel from overheating if
subjected to excessive loads, the EDL cuts out temporarily. The
veh ic le remains operational and behaves in the same way as a
vehic le without EDL.
As soon as the brake has cooled down, EDL switches on again auto ­
matically.
& WARNING
• When accelerating on slippery surfaces, such as on ice or snow,
always be careful when depressing the accelerator pedal. Even
with the EDL working, the drive wheels can spin and reduce your
ability to control your car . - Risk of crash!
• The increased safety afforded by EDL does not mean that you
ca n take safety risks. Always adapt your driving style to the road
conditions and traffic situation.
[ i ] Tips
If a fault occurs in the ABS, the EDL is also not functioning. This is
indicated by the ABS warning
light => page 21. •
Anti-Slip Regulation System (ASR)
The Anti-Slip Regulation System prevents the driven
wheels from spinning when the car is accelerating.
General notes
The Anti-Slip Regulation System (ASR) is integrated in the electronic
stabilization program (ESP) . When the vehicle starts up and acceler­
ates, the wheels are prevented from sp inning by adjus tin g the
engine power to match the amount of grip availab le from the road
surface.
How the system works
ASR performs automatical ly, i.e . w ithout the driver's intervention.
With the aid of the ABS
sensors=> page 240, ASR monitors the
speed of the driven wheels. If the wheels start to spin, the engine
power is reduced automatically until the tires find enough grip to
lock onto the road surface. The system is active across the entire
speed range.
The ASR works in conjunction with the ABS. If a malfunction shou ld
occur in the ABS, the ASR will also be out of act ion.
Activation
The ESP is automatica lly activated when the eng ine is started, and
it performs a self-test. You can activate a deactivated ASR, if
requ ired, by pressing
t h e=> page 236, fig . 199 button .
Deactivation
You can deactivate the ASR, if required, by pressing the button (for
less than 3
seconds) => page 236, fig. 199. With the ASR deactivated,
the ESP check light flashes,
see=> page 22.
Normally, the ESP shou ld always be on, however, it may be advanta­
geous to turn off the system in certai n special cases when some
degree of wheel spin is desired such as :
• when driving with snow chains

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• when driving in deep snow or on a loose surface (to allow the
wheels to dig in to reach firm ground)
• when trying to "rock" the vehicle free when it has become stuck .
The system should be reactivated once you are no longer in such
situations.
Both, the ABS and EDL systems are still functioning even if the ESP
is switched off.
& WARNING
The increased safety afforded by ASR does not mean that you can
take safety risks. Always adapt your driving style to the road conditions and traffic situation.
[ i] Tips
To ensure that the ASR works properly, all four wheels must be fitted
with identical tires Any differences in rolling radius of the tires can
cause the system to reduce engine power when this is not desired.
See
also::::;, page 305, "New tires and replacing tires and wheels". •
Braking
General information
What affects braking efficiency?
Operating conditions and driving habits
The brakes on today's automobiles are still subject to wear,
depending largely on operating conditions and driving
habits::::;, &.
On vehicles which are driven mostly in stop -and -go city traffic or
which are driven hard, the brake pads should be checked by your
authorized Audi dealer more often than specified in the
Mainte­
nance
& Warranty booklet.
Controls and equip­ ment Safety first Vehicle operation
On steep slopes, you should use the braking effect of the engine
.
This way, you prevent unnecessary wear on the brake system. If you
must use your brakes, do not hold the brakes down continuously.
Pump the brakes at intervals.
Moisture or road salt
Under certain conditions, for example, when driving through water
or very heavy rain, or even after washing your vehicle, the braking
effect can be reduced due to moisture (or in freezing conditions ice)
on the brake pads. A few cautious brake applications should dry off
the brake pads or remove any ice coatings.
The effectiveness of the brakes can be reduced when the vehicle is
driven on a salt -covered road and the brakes are not used. Likewise,
you clean off accumulated salt coating from brake discs and pads
with a few cautious applications of the
brake::::;, &.
Corrosion
There may be a tendency for dirt to build up on the brake pads and
corrosion to form on the discs if the car is not driven regularly or
only for short trips with little use of the brakes .
If the brakes are not used frequently, or if corrosion has formed on
the discs , it is advisable to clean off the pads and discs by braking
firmly a few times from a moderately high
speed ::::;,& .
Faults in the brake system
If you should notice a sudden increase in brake pedal travel, then
one of the two brake circuits may have
failed::::;, &.
Low brake fluid level
Malfunctions can occur in the brake system if the brake fluid level is
too low. The brake fluid level is monitored electronically.
& WARNING
• You should perform braking maneuvers for the purpose of
cleaning the brake system only if road conditions permit. Other
road users must not be put at risk - you may cause an accident!
.,.
Vehicle care Do-it-yourself service Technical data

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&, WARNING (continued )
• Before des cending a steep grade , reduce speed and shift trans­
mi ssion into a lo wer gear or lower driving po sition . Do not ride the
brake s or hold the pedal down too long or too often . This could
cau se the brake s to get hot and dimini sh braking efficiency .
• Do not ride the brakes by resting your foot on the ped al when
you do not intend to brake. This may cause the brakes to overheat, premature wear and in creased stopping distan ce.
• Under certain climati c and operating conditions such a s
passing through water, driving in heavy rain or after washing the
v ehicle , the effectiveness of the brakes can be reduced . In winter ,
ice can a ccumulate on the brake pads , linings , discs and drums .
Cautiously apply brakes for a te st. Brakes will dry and ice coating s
will be cleaned off after a few cautious brake applicat ions .
• Driving for an extended period of time on salt-co vered roads
without using your brakes can also affect braking effi ciency . Clean
off accumulated salt coating from brake discs and pads with a few
c autious brake appli cations .
• If you damage the front spoiler , or if you install a different
spoiler , be sure the air flow to the front brakes is not obstructed .
Otherwise the brake system could overheat reducing the effective ­
ness of the entire brake system .
• Failure of one brake circuit will impair the braking capability
resulting in an increased stopping distance . Avo id driving the
vehicle and have it towed to the nearest Audi dealer or qualified
workshop .•
Brake booster
T he brake booster add s ex tra braking power.
The bra ke booster works wit h vacuum pressure which is created
only whe n th e e ng in e is
runn ing=> &,.
& WARNING
• Never let the vehi cle roll to a stop with the engine shut off .
• If the brake booster is not working , for example when towing
your vehicle , or because the brake booster has somehow been
damaged, the brake pedal must be pre ssed considerably harder to
make up for the lack of booster assistance . •
Functioning of Anti-Lock Brake System (ABS)
A BS preven ts th e wh eels fr om lock ing up und er b rak ing.
T he ABS contributes effectively to vehicle contro l since it prevents
th e w heels from
lo cki ng w he n t he brakes a re a ppli ed. T h is mea ns
that the vehicle remains steerable and is less likely to skid.
With ABS you do not need to pump the brake . Just hold the brake
pedal down .
However, do not expect that the ABS shortens braking distance
u nder all circum sta nces. Whe n driving o n gravel or on newly fa lle n
snow on top of icy surfaces, braking distance may be even longer,
t herefore, under these ci rcums tances, it is espec ial ly i mpo rtant th at
you driv e slowly and with great care.
How the ABS system works
An automatic check is made when a speed of about 4 mph (6 km/h)
i s r eac hed . Wh en th is happe ns, a pumpi ng noi se can be hea rd.
I f a n indiv idual wheel be gins to rotat e too slowly i n relation to
vehic le speed and tends to lock, the ABS automatical ly reduces
brake pressur e to prevent tha t whee l from loc king .
Th is a utomatic adjustment process wi ll cause a
slight vibration of
t he brake peda l a nd s om e noi ses t o a lert y ou th at ve hicle spee d
must be adapted to existing road and traffic conditions. _..