2008 AUDI A4 AVANT brake

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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!
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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. _..

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& WARNING
Although the ABS is very effective, always remember that braking
capability is limited by tire traction. Always adjust your driving
speed according to the road and traffic conditions. Do not let the
extra safety afforded by the ABS tempt you into taking extra risks.
The ABS cannot overcome the laws of physics.
[ i] Tips
• If ABS is not functioning properly, a warning light will come on.
See~ page 21.
• If a fault occurs in the ABS , the EDL is also not functioning. This
is indicated by the ABS warning light. •
Brake assistant
The brake assistant is designed to achieve the optimum
braking effect.
The brake assistant helps to increase the effective braking power
and thus to achieve a shorter stopping distance . If the driver
presses the brake pedal very quickly, the brake assistant automati ­
cally boosts the braking force to the maximum level, up to the point
where the anti-lock brake function (ABS) intervenes to stop the
wheels from locking. You should then keep the brake pedal pressed
until the vehicle has braked to the required speed. The brake assis ­
tant switches itself off as soon as you release the brake pedal.
The brake assistant will not be operative if there is a malfunction in
the ABS.
Controls and equip­
ment Safety first
Vehicle operation
& WARNING
Please remember that the accident risk always increases if you
drive too fast, especially in corners or on a slippery road, or if you
follow the vehicle ahead of you too closely. An increased accident
risk cannot be compensated even by the brake assistant, so
always maintain a safe speed. •
Servotronic® -advanced power
steering system
The power steering systems uses the power of the
running engine to allow precise steering with little effort. Your Audi is equipped with the electronically controlled
Servotronic® advanced power steering system. It adjusts
the degree of steering assistance to the roadspeed.
The advanced Servotronic ® power steering system senses the road
speed and electronically adjusts power assistance to provide
comfortable and safe steering response exactly matched to the
vehicle speed .
Power steering will not work if the engine is off. As a result, the
steering wheel will be hard to turn.
The power steering fluid level is checked during the scheduled
maintenance services.
0 Note
If there is an electronic malfunction, servotronic will still function
like a conventional power steering system, providing a constant
steering support force that is no longer proportionate to the vehicle
speed . This is most noticeable when turning the steering wheel at
low speeds (for example when parking), -more effort will be
required than usual.
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Vehicle care Do-it-yourself service Technical data

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Driving and environment
The first 1,000 miles (1,500 km) and
afterwards
New engine
The engine needs to be run-in during the first 1,000 miles
(1,500 km).
For the first 600 miles (1,000 kilometers):
Do not use full throttle.
- Do not drive faster than 3/4 of the top speed marked on
the speedometer.
- Avoid high engine speeds .
From 600 to 1,000 miles (1,000 to 1,500
kilometers):
- Speeds can gradually be increased to the maximum
permissible road or engine speed.
During and after break-in period
- Do not rev the engine up to high speeds when it is cold.
This applies whether the transmission is in N (Neutral) or
1n gear.
After the break-in period
- Do not exceed maximum engine speed under any
circumstances.
- Upshift into the next higher gear
before reaching the red
area at the end of the tachometer
scale => page 12.
Controls and equip­
ment Safety first
Vehicle operation
During the first few hours of driving, the engine's internal friction is
higher than later when all the moving parts have been broken in.
How well this break-in process is done depends to a considerable
extent on the way the vehicle is driven during the first 1,000 miles
(1,500 kilometers).
0 Note
Extremely high engine speeds are automatically reduced. However,
these rpm-limits are programmed for an engine well run-in, not a
new
engine.
~ For the sake of the environment
Do not drive with unnecessarily high engine speeds -upshifting
early saves fuel, reduces noise and protects the environment .•
New tires
If your vehicle is running on new tires, drive particularly
careful for the first 350 miles (500 kilometers) after fitting.
& WARNING
New tires tend to be slippery and must also be "broken-in". Be
sure to remember this during the first 350 miles (500 kilometers).
Brake
gently. Avoid following closely behind other vehicles or
other situations that might require sudden, hard braking.
•
Vehicle care Do-it-yourself service Technical data

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New brake pads
Remember that new brake pads do not have a full braking
effec t during the first 250 miles (400 kilometers) after they
are i nstalled .
New brake pads have to be "burn ished in" befo re they have opti mal
grab =>& .
During the break -in period, you s hou ld avo id putti ng severe loads
on the brakes . Severe loads include, for examp le, sudden hard
braking, in particular at very h igh speeds or, for example, on moun ­
t ain passes .
& WARNING
New brake p ad s don't h ave th e be st sto pping p ower a nd mu st b e
" brok en -in " durin g th e initial 100 to 1 50 mil es (150 t o 200 kil ome ­
t e rs) of norm al cit y dri ving . You can comp en sa te for thi s by
pr ess ing the brak e ped al mor e firmly . Thi s al so appli es later when
ne w pad s a re in sta lled. •
Catalytic converter
It is very important that your emission control sys tem
(catalytic conver ter) is functioning properly to ensure that
y o ur vehicle is running in an environmentally sound
manner.
-Always use lead-free gasoline => page 267, "Fuel supply".
-Never run the tank down a ll the way to empty.
-Never put too much motor o il in your engine => page 278,
"Add ing eng ine oil -Neve r try to push -or tow -s ta rt yo ur vehic le.
The catalytic converter is an efficient "clean-up " device built into the
exhaust system of the vehicle. The catalyt ic converter burns many
of the po llutants in the exhaust gas before they are released into the
atmosphere.
T he exc lusive use o f un leaded fue l is critica lly important for the l ife
of the catalytic converter and proper functioning of the engine.
& WARNING
• Do not park or operate th e veh icle in ar eas wh ere the hot
ex hau st sys tem m ay come in contac t w ith dr y gra ss, bru sh , fuel
s pill or other material which can cau se a fire .
• Do not appl y additi ona l under coating or ru stpr oofing on or
ne ar the e xhau st m anifol d, ex haust pipe s, ca ta lytic converter or
he at shield s. Du ring dri ving , the sub sta nce u sed f or under coating
c ould overhe at and cau se a fir e.
0 Note
• Be aware that just one tank filling with leaded fue l wi ll already
ser iously degrade the performance of the catalyt ic converter.
• Do not exceed the correct engine oi l
level=> page 278.
• Do not drive until the fuel tank becomes comp letely empty . The
engine could misfire . Unburned fuel could also get into the exhaust
system and this could cause the catalytic conver ter to overheat .
• Do not turn off the ignition wh ile the vehicle is moving.
• Do not continue to operate your vehicle under these conditions,
as otherwise fuel can reach the cata lyt ic converter . This cou ld result
in overheating of the converter, requiring its rep lacement .
• To assure eff icient operat ion of the Em iss ion Control System:
- Have your vehicle maintained properly and in accordance with
the service recommendations in your Maintenance
& Warranty
booklet.
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