2008 AUDI A4 AVANT brake light

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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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&, 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.
.,.
Vehicle care Do-it-yourself service Technical data

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- Lack of proper maintenance as wel l as improper use of the
vehic le wi ll impair the func tion of the emission control system
and cou ld lead to damage .
<£> For the sake of the envir onm ent
Even when the Emission Control System is operating properly, the
exhaust gas can have a su lfur -like exhaust gas sme ll under some
operat ing states . Th is depends on the sulfur content of the fuel
being used. Using a different brand of fue l may he lp, or fil ling the
tank with lead -free super grade gasol ine. •
Avoid damaging the vehicle
When you are driving on poor roads, or over curbs, steep ramps,
e tc., make certain that low- lying parts such as spoilers and exhaust
system parts do not bottom out and get damaged.
This is especial ly true for vehicles with low -s lung chassis (sports
chassis)* and ful ly loaded vehicles .•
Operate your vehicle economically
and minimize pollution
General
Y o ur personal style of driving will determine the economy
of your vehicle, as well as exhaust and noise levels.
Fuel economy, env ironmental impact, and wear on your engine,
brakes and t ires largely depend on three factors :
• your personal driving sty le
• operat ing cond it ions
• technica l limitat ions
Controls and equip­
ment Safety first Vehicle operation
If you anticipate what you need to do next and drive economica
lly,
you can easily cut your fuel consumptio n by 10 -15 percent . This
section wil l give you some tips on how you can help the environ­
ment and your pocketboo k.
[ i ] Tips
The cons umption estimates as pub lished by ENV IRO NM EN TAL
PRO TECTION AGENCY (EPA) and Transport Canada may not corre ­
spond to your actua l consumption on the road, which wi ll vary
depending upon veh icle load and speed, road and weather condi ­
tions, trip length, etc. •
Drive smoothly and keep a lookout ahead
Vehicles use the most fuel when they ore accelerating .
-Avoid unnecess ary accelerating and brak ing.
Vehic les use the most fue l when they are accelerating . If you ant ici ­
pate what is going to happen ne xt, you wi ll need to brake less and,
thus , acce lerate less. Let the vehicle coast whenever poss ib le -for
examp le when you see that the next traffic light is red. •
Avoid full throttle
Driving at moderate speeds saves fuel and improves your
mileage.
- Try and keep we ll below your car 's max imum speed.
Acce lerating gent ly reduces fue l consump tion , engine wear, and
does no t disturb the environme nt.
Fue l consumption, exhaust emissions and engine noise increase
disproportionately at h ig h speeds . If you drive at approx imate ly
three quarters of top speed, fuel consumpt ion wil l be reduced by _,,,
Vehicle care Do-it-yourself service Technical data

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Trailer towing
Driving with a trailer
General information
Your Audi was designed primarily for passenger transpor­
tation.
If you plan to tow a trailer, please remember t hat the add it ional load
wi ll affect durability, economy and performance.
Trailer towing not only p laces more stress on the veh icle, it a lso ca lls
for more concentration from the driver.
For th is reasons, always fo llow the operating and dr iving instruc ­
t ions provided and use common sense. •
Technical requirements
Trailer hit ch
Use a weight -carrying hitch conforming to the gross trailer weight.
The hitc h must be suitab le for your veh ic le and tra iler and must be
mounted securely on the vehicle's chassis at a technically sound
l ocation. Use only a tra iler hitch with removable bal l mount. A lways
check with the trai ler hitch manufacturer to make sure that you are
using t he correct hitch .
Do not use a bumper hit ch .
The hitch must be installed in such a way that it does not interfere
with the impact-absorb ing bumper system . No mod ifications
shou ld be made to the vehicle exhaust and brake systems. From
time to time, check that all hitch mount ing bo lts re main securely
fastened.
When you are not towing a trai ler, remove the trailer hit c h ball
mount. Th is prevents the hitch from causing damage s hou ld your
vehic le be struck from
behind ~& .
Tire pre ssure
When towing a trailer, inf late the tires of your vehic le to the cold tire
pressure listed under "Full load" on the s ticker on the right door­
jamb . Inflate trai ler tires to tra iler and tire manufacturers' specifica­
t ions.
Lights
T he head ligh t settings shou ld be checked with the trailer at tached
before driving off. Have the head lights adjusted as necessary so
t hat you can see t he road ahead bu t not bl ind oncom ing traffic.
Check to make sure both vehicle and trailer lights are working prop ­
e rly .
Engine cool ing sy stem
Towing a t railer makes the eng ine work ha rder. It is imp ortant tha t
the cooling system's performance stands up to the additiona l
strain. Make sure that the coo ling system has enoug h fluid.
Traile r br ake s
If your tra ile r i s eq uipped wi th a braki ng system, check to be s ure
that it conforms to al l regu lations .
T he tra iler hydraulic brake system must no t be direct ly connected to
the vehic le's hydrau lic brake system .
Safety chains
Be sure trailer safety chains are properly connected from the trai ler
t o the h itch on the vehicle. Leave enough s lack in t he chains to
permit turning corners. When you install safety chains, make sure
they will not drag on the road when you are driving.
T he chains shou ld cross under t he trailer tongue to prevent it from
dropping in case of separation from the hitch. _,,,

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Trailer lights
Trailer lights must meet all regulations. Be sure to check with your
authorized Audi dealer for correct wiring, switches and relays .
Mirrors
If you are unable to see the traffic behind you using the regular
outside mirrors, then you
must install extended mirrors. It is impor ­
tant that you
always have clear vision to the rear .
& WARNING
After removing the trailer hitch, do not store it in your vehicle. In
case of sudden braking, the hitch could fly forward and injure you
or your passengers. •
Operating instructions
Maximum trailer weight
A trailer for your vehicle is limited to a typical class 1 or class 2
trailer .
Trailer load distribution
Be sure the load in the trailer is held securely in place to guard
against shifting, be it forward, backward or sideways.
Never allow a passenger to ride in a trailer~ & in "Driving instruc­
tions".
Tire pressure
When towing a trailer, inflate the tires of your vehicle to the cold tire
pressure listed under "Full load" on the sticker on the right door­
jamb. Inflate trailer tires to trailer and tire manufacturers' specifica­
tions .
Controls and equip­
ment Safety first Vehicle operation Lights
The
headlight settings should be checked with the trailer attached
before driving off. Adjust as necessary so that you can see the road
ahead but not blind oncoming traffic.
Check proper working of vehicle and trailer lights .
Power Supply
The power supply to the trailer is disconnected when the ignition
key is removed.
Safety chains
Be sure trailer safety chains are properly connected from the trailer
to the hitch on the vehicle . Leave enough slack in the chains to
permit turning corners. When you install safety chains, make sure
they will not drag on the road when you are driving.
The chains should cross under the trailer tongue to prevent it from
dropping in case of separation from the hitch.•
Driving instructions
Driving with a trailer always requires extra care and
consideration.
To obtain the best possible handling of vehicle and trailer,
please note the following:
- Do not tow a loaded trailer when your car itself is not
loaded.
- Be especially careful when passing other vehicles.
- Observe speed limits.
- Do not drive at the maximum permissible speed.
- Always apply brakes early.
- Monitor the temperature gauge.
Vehicle care Do-it-yourself service Technical data

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W eig ht d is tri buti on
Towing a loaded tra iler wit h an empty car resu lts in a high ly
unstable distribution of weight . If this cannot be avoided drive at
ve ry low speeds only to avo id the risk of losing steering control.
A "ba lanced" rig is easier to operate and control. This means that
the tow vehicle should be loaded to the extent possible and permis ­
sib le whi le keeping the trailer as light as possib le under the circum ­
stances. Whenever possible, transfer some cargo to the luggage
compar tment of the tow veh icle whi le observi ng tongue load
requirements and vehicle loading considerations.
Speed
T he higher the speed, the more difficu lt it becomes for the driver to
contro l the rig . Do not drive at the maximum permissible speed.
Reduce your speed even more under unfavorable load, weather or
wind conditions -part icularly when going dow nh ill.
Reduce vehicle speed
immedi ately if the trailer shows the slightest
sign of swaying.
Do not tr y to stop the s waying by a cceler ating .
Observe speed limits . In some areas speeds for veh ic les towi ng
trai lers are lower than for regular vehicles.
Always app ly brakes early. When driving downhi ll, shift into lower
gear to use the engine braking effect to slow down the vehicle. Use
of the brakes alone can cause them to overheat and fail.
C oo la nt tempe ra tu re
The coola nt temperature gauge => page 13 must be observed care ­
ful ly. If the needle moves close to the upper end of the scale, reduce
speed immediately and/or switch off the air conditioner.
If the coolant te mperature warning light in the instrument cluster
starts
flashing -~-, pul l off the road, stop and let the engine idle for
about two minutes to prevent heat build -up .
& WARNING
An yone not p rop erl y res trained in a mo ving vehicl e is at a much
gre ate r risk in an accident. Never let an yone rid e in your car who
is not p rop erl y wear ing the re stra int s pro vided b y Aud i. •
Trailer towing tips
Important to know
Your vehicle handles differently when towing a tra iler because of
the additional weight and weight distribution. Safety, performance
and economy wi ll great ly depend on how carefu lly you load your
trai ler and operate your rig.
Before you actual ly tow your tra iler, practice turning, stoppi ng and
backing up in an area away from traffic. Keep practicing unti l you
have comp letely become familiar with the way yo ur vehicle -trailer
combination behaves and responds .
Backing up is difficu lt and requires practice. Backing up with a
trai ler genera lly requ ires steering action oppos ite of that when
backing up your vehic le without a trailer.
Mainta in a greater distance between you r vehic le and the one in
front of you. You will need more room to stop.
To compensate for the trai ler, you wi ll need a larger than normal
t urning radius .
When passing, remember that you cannot accelerate as fast as you nor mally wou ld because of t he added load . Make sure yo u have
enough room to pass. After passing, al low plenty of room for your
trai ler before changing lanes again .
Avo id jerky starts, sharp turns or rapid lane changes.