wheel AUDI S8 2008 Service Manual

Airbag system -
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& WARNING (continued)
• If you must install a rearward facing child seat on the front
passenger seat because of exceptional circumstances and the
PASSENGER AIR BAG OFF light does not come on and stay on,
immediately install the rear-facing child seat in a rear seating posi­
tion and have the airbag system inspected by your Audi dealer.
& WARNING
If, in exceptional circumstances, you must install a forward-facing
child restraint on the front passenger's seat:
• Always make sure the forward-facing seat has been designed
and certified by its manufacturer for use on a front seat with a
passenger front and side airbag.
• Never put the forward-facing child restraint up against or very
near the instrument panel.
• Always move the passenger seat into its rearmost position in
the seat's fore and aft adjustment range, as far away from the
airbag as possible, before installing the forward-facing child
restraint. The backrest must be adjusted to an upright position.
• Make sure that the PASSENGER AIR BAG OFF light comes on
and stays on all the time whenever the ignition is switched on. •
Advanced Airbag System components
The front passenger seat in your vehicle has a lot of very important
parts of the Advanced Airbag System in it. These parts include the
weight -sensing mat, sensors, wiring, brackets, and more. The func ­
tion of the system in the front passenger seat is checked by the elec­
tronic control unit when the ignition is on. The control unit monitors
the Advanced Airbag System and turns the airbag indicator light on
when a malfunction in the system components is detected. The
function of the airbag indicator light is described in greater detail below . Because the front passenger seat contains important parts
Controls and equip­
ment Safety first Vehicle operation
of the Advanced Airbag System, you must
take care to prevent it
from being damaged. Damage to the seat may prevent the
Advanced Airbag for the front passenger seat from doing its job in
a crash.
The front Advanced Airbag System consists of the
following:
• Crash sensors in the front of the vehicle that measure vehicle
acceleration/deceleration to provide information to the Advanced
Airbag System about the severity of the crash.
• An electronic control unit, with integrated crash sensors for front
and side impacts. The control unit "decides" whether to fire the
front airbags based on the information received from the crash
sensors. The control unit also "decides" whether the safety belt
pretensioners should be activated.
• An Advanced Airbag with gas generator for the driver inside the
steering wheel hub.
• An Advanced Airbag with gas generator inside the instrument
panel for the front passenger.
• A weight -sensing mat under the upholstery padding of the front
passenger seat cushion that measures the total weight on the seat.
The information registered is sent continuously to the electronic
control unit to regulate deployment of the front Advanced Airbag on
the passenger side .
• An airbag monitoring system and indicator light in the instru­
ment
cluster => page 229.
• The PASSENGER AIR BAG OFF light comes on and stays on in the
center of the instrument
panel => page 230, fig. 233 and tells you
when the front Advanced Airbag on the passenger side has been
turned off .
• A sensor below the safety belt latch for the front seat passenger
to measure the tension on the safety belt . The tension on the safety
belt and the weight registered by the weight-sensing mat help the
control unit
"decide" whether the front airbag for the front
passenger seat should be turned off or
not=> page 220, "Child
restraints on the front seat
-some important things to know". .,_
Vehicle care Do-it-yourself service Technical data

__ ....!:,A~i'.!. r !::b :!a ~g:L.: s~ y~ s:!: t::.:: e~ m'..!.!.. ______________________________________________ _
or the low er parts of the body . Front airbags only supplement th e
th re e po int safe ty b elts in som e front al c ollis ions in which the
vehic le dece lerat ion is h igh enou gh to deploy the a irba gs.
Front airbags will not deploy:
• if the ignition is switched off when a crash occurs,
• i n sid e coll is io ns,
• in r ear- e nd collisi ons ,
• in ro llovers,
• when th e cras h de cele ration meas ured b y th e a irba g sys tem is
less than the mini mum threshold needed for a irbag deployme nt as
r egi stere d by th e ele ctr on ic con trol uni t.
The front passenger airbag will also not deploy :
• when th e front p asseng er seat is not occ upi ed ,
• when the weight on the front pas senge r seat a s sensed by the
A dvance d Airb ag Syste m indicates t hat th e fr on t airb ag on the
passenger side has to be t urned off b y the e lectronic control unit
(the PASSENGER AIR BAG OFF li g ht come s on and s tays o nl.
& WARNING
Sitting in the wrong position can increase the risk of serious injury
in crashes .
• To reduce the risk of injury when the airbags inflate , the driver
and passengers must always sit in an upright position , must not
lean against or place any part of their body too close to the area
where the airbags are located.
• Oc cupants who are unbelted , out of position or too close to the
airbag can be seriously injured by an airbag as it unfolds with
great force in the blink of an eye
=> page 220.
& WARNING
A child in a rearward -facing child seat installed on the front
passenger seat will be seriously injured and can be killed if the
front airbag inflates - even with an Advanced Airbag System .
• The inflating airbag will hit the child seat or infant carrier with
great force and will smash the child seat and child against the
backrest , center arm rest , door or roof .
• Always install rear-facing child seats on the rear seat.
• If you must install a rearward facing child seat on the front
passenger seat because of exceptional circumstances and the
PASSENGER AIR BAG OFF light does not come on and stay on ,
immediately install the rear-facing child seat in a rear seating posi­
tion and have the airbag system inspected by your Audi dealer.
& WARNING
Objects between you and the a irbag will increase the risk of injury
in a crash by interfering with the way the airbag unfolds or by
being pushed into you as the airbag inflates.
• Never hold things in your hands or on your lap when the vehicle
is in use.
• Never transport items on or in the area of the front passenger
seat. Objects could move into the area of the front airbags during
braking or other sudden maneuver and become dangerous projec­
tiles that can cause serious personal injury if the airbags inflate.
• Never place or attach accessories or other objects (such as cup
holders, telephone brackets, large , heavy or bulky objects) on the
doors , over or near the area marked
"AIRBAG " on the steering
wheel , instrument panel , seat backrests or between those areas
and yourself . These objects could cause injury in a crash, espe­
cially when the airbags inflate .
• Never recline the front passenger's seat to transport objects .
Items can also move into the area of the side airbag or the front
airbag during braking or in a sudden maneuver. Objects near the .,_

__ .....;.A..;.;.;. ir.;;b ;..; a;;;;. g=... s;;;.!. y.;;s ..;;t ..;;e ;.;.m.;..;... ________________________________________________ _
&, W ARNING (continued )
• A tight tether or other strap on a rearward-facing child restraint
attached to the front passenger seat can put too much pres sure
on the weight-sensing mat in the seat and reg ister more weight
than is actually on the seat. The heavier weight registered can
make the system work as though an adult were on the seat and
deploy the Advanced Airbag when it must be suppressed causing
serious or even fatal injury to the child .
• If, in exceptional circumstances, you must install a forward ­
facing child restraint on the front passenger seat , always move the
seat into its rearmost position in the seat's fore and aft adjust­
ment range , as far away from the a irbag as possible. The backrest
must be adjusted to an upright position. Make sure that the
PASSENGER AIR BAG OFF light comes on and stays on all the time
whenever the ignition is switched on .
& WARNING
• If the PASSENGER AIR BAG OFF light does not go out when an
adult is sitting on the front passenger seat after tak ing the steps
described above, make sure the adult i s properly seated and
restrained at one of the rear seating positions .
• Have the airbag system inspected by your Audi dealer before
transporting anyone on the front passenger seat .
[ i] Tips
If the we ight -sens ing mat in the front passenger seat detects an
e mp ty s eat, th e front air bag o n the pass enge r sid e wil l be tur ned
off, and PASSENGER AIR BAG OFF will stay on.•
Repair, care and disposal of the airbags
Parts of the airbag system are insta lled at many different places o n
yo ur Au di. In stal li n g, r emo vin g, s ervic ing or rep airi ng a part i n an area of the vehicle can damage a part of an airbag system and
p re vent that sys tem from wor king pr operly in a c ollis ion.
Th ere are some important th ings you hav e to know to ma ke sure
that t he effectivenes s of the system will not be impai red and that
discar ded co mponents do not ca use injury o r po llut e the enviro n­
ment .
& WARNING
Improper care , servicing and repair procedures can increase the
risk of personal injury and death by preventing an airbag from
deploying when needed or deploying an airbag unexpectedly:
• Never cover , obstruct , or change the steering wheel horn pad
or airbag cover or the instrument panel or modify them in any way .
• Never atta ch any objects su ch as cup holders or telephone
mountings to the surfaces covering the airbag units .
• For cleaning the horn pad or instrument panel, use only a soft,
dry cloth or one moistened with plain water. Solvents or cleaners
could damage the airbag cover or change the stiffness or strength
of the material so that the airbag cannot deploy and protect prop­
erly .
• Never repair , adjust, or change any parts of the airbag system .
• All work on the steering wheel, instrument panel , front seats or
electrical system (including the installation of audio equipment ,
cellular telephones and CB radios , etc .I 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 :
~

___ A_ ir_b _ a_ g=- s-a. y_s _t _e _m _________________________________________________ _
If the front airbags deploy, the knee airbags also dep loy in frontal
c oll is ions above a ce rtain sever ity.
When the system is deployed, the airbags start to fi ll with a prope l­
lant gas, and inflate between the lower part of the inst rument pane l
and t he dr iver a nd t he lowe r part o f th e instrument pane l and t he
front
passenge r=> page 227 , fig. 232 .
Al tho ug h t hey a re not a soft p illow, t hey ca n "cushion" th e im pact
and in th is way they can he lp to r educe th e ris k of injury to the lower
e xtr em it ie s.
A ll thi s takes place insta nta ne ous ly, so fast t hat m any peop le do n't
even rea lize that t he ai rbags have deployed. The ai rbags a ls o inflate
wi th a gre at de al o f fo rc e an d it is impo rta nt for occu pant safet y th at
not hing s hou ld be in t heir wa y when they dep lo y.
Fu lly in flate d ai rb ags in co mbin ati on w ith p ro perly w orn s afety b elt s
s low down and limit the occupant's for ward mov eme nt and he lp to
r e duc e th e risk .•
Important safety instructions on the knee
airbag system
A irbags a re only s uppl emen tal rest raints. A lway s w ear
safety belts co rrectly and rid e in a p rope r seat ing po sition .
There i s a lo t th at you and yo ur pass eng ers m ust kno w and do t o
he lp th e safet y be lts and ai rbags to p rovide supp lemental protec­
ti on.
& WARNING
An inflating knee airbag can cause serious injury. Wearing safety
belts incorrectly and improper seating positions increase the risk
of serious personal injury and death whenever a vehicle is being
used .
• The airbag system cannot protect you properly if you are
seated too close to any of the airbag locations . When adjusting
& WARNING (continued)
their seat positions, it is important that both the driver and the
front passenger keep their upper bodies and knees at the
following minimum safe distances :
- 1
O inches (25 cm) between the chest and the steering
wheel/instrument panel .
- 4 inches (10 cm) between the knees and the lower part of the instrument panel.
• The risk of personal injury increases if you lean forward or to
the side, or if the seat is improperly positioned and you are not
wearing your safety belt . The risk increases even more should the
airbag deploy .
• Always make sure that the knee airbag can inflate without
interference . Objects between yourself and the airbag can
increase the risk of injury in an accident by interfering with the
way the airbag deploys or by being pushed into you as the airbag
deploys.
- No persons (children) or animals should ride in the footwell
in front of the passenger seat . If the airbag deploys, this can
result in serious or fatal injuries .
- No objects of any kind should be carried in the footwell area
in front of the driver's or passenger's seat. Bulky objects (shop­
ping bags , for example) can hamper or prevent proper deploy­
ment of the airbag . Small objects can be thrown through the
vehicle if the airbag deploys and injure you or your passengers .
• Make sure there are no cracks , deep scratches or other damage
in the area of the instrument panel where the knee airbags are
located.
• If children are incorrectly seated , their risk of injury increases in
the case of an accident
=> page 243 , "Child Safety". •

11111 Child Safety
------!....------------------------------
&, W ARNING (continued )
• Alway s inst all rear-facing child safety seats on the rear seat .
• If you mu st in sta ll a rear ward f acing child safet y seat on the
front pa ssenger seat in exceptional circum stan ces and the
PASSENGER AIR BAG OFF light doe s not come on and stay on,
immediately inst all the rear-facing child safety seat in a rear
s eating po sition and ha ve the airbag sy stem inspe cted immedi ­
atel y by your Audi de aler .
& WARNING
If, in exceptional circumstance s, you mu st in stall a forward -facing
c hild re straint o n the fr ont p assenger 's seat:
• Alway s make sure the forward -fa cing s eat ha s been de signed
a nd cert ified by it s m anufa cturer for use on a front seat w ith a
pa ssenger front and side airbag.
• Always follow the manufacturer's instruct ions provided with
the child safety seat or carrier.
• Alway s move the pa ssenger seat into it s re armost position in
the seat' s fore and aft adju stment range , as far aw ay from the
ai rbag as possibl e befo re installing the ch ild restr aint . The ba ck­
rest mu st be adjusted to an upright po sition.
• Alway s m ake sure that the PASSENGER AIR BAG OFF l ight
c ome s on and stays on all the time whenever the ignition is
sw it c hed on . •
Advanced front airbag system and children
Your vehicle is equipped with an "Advanced Airbag System" in
compl iance with U nited States Federa l Motor Vehicle Safety Stan­
dard { FMVSSl 208 as applicable at the time your vehicle was manu ­
factured. T
he Advanced Airbag system in your vehicle has been certified to
meet the " low -risk" requirements for 3 and 6 year -old chi ldre n on
the passenger side and smal l adults on the driver side . The low risk
deployment criteria are intended to reduce the risk of injury through
interaction with the 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 up to 12 months who are restra ined on
the front passenger seat in child restraints that are listed in the
Standard.
Even though your vehic le is equipped with an Advanced Airbag
system, al l ch ildren, especially those 12 years and you nger, should
a lways ride in the back seat properly restrained for their age and
size . The airbag on the passenger side makes the front seat a poten­
tia lly dangerous p lace for a ch ild to ride. The front seat is not the
safest p lace for a child in a forward -facing child safety seat . It can be
a very dangerous p lace for an infant or a larger ch ild in a rearward ­
facing seat. •
Advanced Airbags and the weight-sensing
mat in the front seat
The Advanced Airbag Sys tem in your vehicle detects the presence
of an infant or child in a chi ld restra int on the front passenger seat
using the weight -sensing mat in the seat cushion and the sensor
below the safety belt latch on the front passenger seat that measures the tension on the safety belt.
T he weigh t-sensing mat measures total weight o f the chi ld and the
child safety seat and a child blanket on the front passenger seat . T he
weig ht o n the fr ont passenger seat is rela ted to the desig n of the
chi ld restraint and its "footprint", the size and shape of the bottom
of the child restraint as it sits on the seat . The weight of a child
restraint and its "footprint" vary for different kinds of child
~

____________________________________________ ln_t_ e_ l_ li _,..g "- e_ n
_ t_t_e _ c_ h_ n_o _l_o _....g ,_,y'-_IJIII
T he direction in which the driver wishes to travel is determined with
t he aid of the steering angle and vehicle speed and is con tinua lly
compared with the actual behavior of the vehicle. If the two do not
match, for example, when the vehic le starts hydrop laning on a wet
road, ESP will automatically brake the appropriate whee l to correct
the prob lem.
The vehicle is then stabi lized by the forces act ing on the whee l
during braking. If the vehicle is
oversteering (rear tends to skid out
of the turn), the brakes are mainly 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), t he brakes are applied a t the
rear wheel that is on the inside of the curve. An acoustic signal indi ­
cates when ESP brake app lication cuts in
=> & .
The system operates across t he entire speed range in comb inat ion
with the ABS system
=> page 272 . If the Anti -Lock Brake System
(ABS) malfunctions, the ESP wi ll be out of act ion as well.
Ac tivation
When you turn on the eng ine, ESP will automatically be activated
and wil l perform a self -test.
The system can be activated or deactivated by pressing the but ton
=> page 268, fig. 254 . The warning light comes on when the system
is switched off
=> page 18.
Normally, the ESP s hould always be on, however, it may be advanta­
geous to turn off the system in certain special cases when some
degree of wheel spin is des ired such as:
• when driving with snow chains
• whe n driving in deep snow or on a loose surface (to allow the
whee ls to dig in to reach firm ground)
• whe n trying to
"rock" the vehicle free whe n it has become stuck.
T he system should be reactivated once you are no longer in such
situations .
Both the ABS and EDS systems are still functioning even if the ESP
is switched off .
Controls and equip­
ment Safety first Vehicle operation
& WARNING
The Ele
ctron ic Stabiliz ation Pr ogram i s ne verthele ss subje ct to the
laws of phy sic s. It is p articularl y important to pay attention to this
fa ct on wet and slipper y ro ad s. It i s therefore important th at you
alway s adapt your dr iving to the condit ion of the road and traffic
c ondition s. Do not allo w the in crea sed safety pro vided by the Ele c­
tronic Stabilization Program system to lull you into a ccepting
a ddition al safety ri sk s.
•
Electronic differential lock (EDL)
The elec tronic d ifferen tial lock moni tors the rotation al
s p eed of the drive wheels.
G en era l not es
The elect ronic d ifferential lock (EDU helps the ca r to start mov ing,
accelerate and c limb a grad ient on surfaces providing poor or
a lmost no grip . Without EDL, this would be difficult, if not impos ­
s ib le.
How the syst em works
The EDL operates automatical ly. It monitors the rotationa l speed of
t he drive wheels on an ax le with the he lp of the ABS senso rs
=> page 272. If a not iceable difference in rotational speed between
the drive wheels on one axle is detected (e.g. on slippery ground
on
one side),
the spinning w heel is bra ked, thereby transferring power
to the other drive wheel or wheels (a ll -whee l drive) . This is done up
t o a speed of ab out 60 mph (100 km/h). N oises from the brake
system signal that wheel spin is being control led .
Dri ving off
When driving off, always be sure to keep road conditions in mind as
you accelerate. I f one drive wheel spins because it is on a sur face
with less grip, gradual ly increase the pressure on the accelerator
pedal unt il the car star ts to move . The whee l less able to t ra nsfer
power spins.
.,,
Vehicle care Do-it-yourself service Technical data

llll.___l_n _t _e _ll _ig=- e_n _ t_ te_ c_h _n_ o_ lo...;g'"'-=- y ___________________________________________ _
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
vehicle remains operational and behaves in the same way as a
vehicle 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
can 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
stabili zation program (ESP) . When the vehicle starts up and acceler­
ates, the wheels are prevented from spinning by adjusting the
engine power to match the amount of grip available from the road
surface.
How the system works
ASR performs automatically, i.e. without the driver's intervention.
With the aid of the ABS
sensors=> page 272, 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 should
occur in the ABS, the ASR will also be out of action.
& 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 336, "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
Warranty &
Maintenance booklet. _,,,

-Intelligent technology
P:V:1--------=-- --=-=-------------
& WARNING
• Never let the vehi cle roll to a stop with the engine shut off .
• If the brake boo ster i s not working, for example when towing
your vehicle , or because the brake booster has so mehow been
damaged, the brake pedal must be pres sed considerably harder to
make up for the la ck of booster as sistan ce . •
Functioning of Anti-Lock Brake System (ABS)
AB S pre vent s th e wh eels fr o m lo ckin g up un der braking .
The ABS contributes effective ly to ve hicle control s ince it prevents
th e whee ls from
lo cking w hen t he brakes are a ppl ied. This 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.
H owever, do not expect the ABS to shorten braking distance under
all cir cum stances. W hen drivin g on g ravel o r on new ly fallen s now
on top of icy surfac es, bra king distance may be even longer, there ­
fo re, unde r th ese circum stances, i t is especially i mporta nt th a t yo u
drive slow ly and with great care .
How the ABS system works
An automatic check is made when a speed of about 4 mph (6 km/h)
is reac hed . When this ha p pens, a pumping n oise can be hea rd.
If an indiv idua l wheel begins to rotate too s lowly in relation to
vehic le speed and tends to lock, the ABS automatica lly reduces
brake pressure to prevent that whee l from loc king .
T his automat ic adjustment process wil l cause a
slight vibration of
th e br ak e pe dal a nd some noises to ale rt you th at ve hic le sp eed
must be adapted to existing road and traffic conditions.
& WARNING
Although the ABS is very effe ctive , always remember that braking
capability is limited by tire traction. Alway s adjust your driving
speed a ccording to the road and traffi c 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
• I f ABS is not funct io ni ng properl y, a wa rn ing li ght will co me o n.
See ~ page 21.
• I f a fault occurs in the A BS, the EDL is also not functioning. This
i s indica ted by the ABS wa rn ing l igh t.•
Brake assistant
The brake assis tant is desig ned to ach ieve the o ptim um
brakin g eff ec t.
The br ake assistan t helps to in cr eas e the effec tive b raki ng pow er
and thus to achieve a shorter stopping distance . If the driver
p re sses the b rake pe dal very q uick ly, the brake assistan t auto mati ­
ca lly boosts the brakin g force to the maximum level, up to th e point
whe re the a nti-lock b rake functi on (AB S) int ervenes to sto p the
w hee ls from loc king . You s hou ld t hen k eep th e br ake pedal pressed
until t he vehicle ha s braked to the required speed . The brake a ssis ­
t ant s witches itse lf off as soo n as you re lease t he bra ke pedal.
T he b rake assistant will not be ope rative if there is a malfunction in
th e ABS .
& 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 . Increased risk of an
~

Intellig ent tec hnol ogy -
------------ -=--=-= '-
& WAR NIN G (c onti nued )
acc ident canno t b e co mp ensat ed for even b y th e br ake assis tant,
s o alway s maintain a safe sp eed . •
Servotronic® - advanced power
steering system
The power steering systems uses the power of the
running engine to allow precise s teering with little effor t.
The advanced Servotronic® power steering system senses the road
speed and electronically adjusts power assistance to provide
comfortab le and safe steer ing response exactly matched to the
vehic le speed.
Power s teeri ng will not work if the engine is off . As a result, the
steering whee l wil l be hard to turn .
The power steering fluid level is checked during the scheduled
maintenance serv ices.
0 Note
If there is an electron ic ma lfunction, servotronic will sti ll funct ion
like a conventiona l power steering system, providing a constant
steer ing suppor t force that is no longer proportionate to the vehicle
speed . This is most noticeable when turning the steering wheel at
low speeds (for examp le w hen parking), -more effor t wi ll be
required than usual.
• Be aware of the different than usua l steering response and
adjust your steering force accordingly .
• Have the problem checked and set right by an Aud i dea ler as
soon as possib le.
Controls and equip­ ment Safety first Vehicle operation
[
i ] Tip s
• When the engine is running, never hold the steer ing whee l
turned all the way to the right or to the left for longer than 15
seconds. The power steer ing pu mp wil l overheat the hydraul ic fluid
if you keep ho lding the steering whee l turned a ll the way. This is
like ly to damage the power steering system.
• I f the power steering system shou ld fail entire ly, or if the engine
is not runn ing ( for examp le, wh ile be ing towed), you w ill st ill be able
to steer the vehicle . However, considerably more effort will be
requ ired to do so.
• I f the power steering system shou ld have a leak, or is not func ­
tioning properly, contact your author ized Audi dealer im mediately.
• The power stee ring system requires a special ly formulated
hydrau lic fluid . The power steer ing reservo ir is the one located most
forward on the left side of the engine
compartment => page 308. The
correct flu id level in the reservo ir is important for proper func ­
tioning of the power steering. •
Driving with your quattro®
With All Wheel Drive, all four wheels are driven.
Genera l inf orm ati on
With All Whee l Drive, power is d istributed to all fo ur wheels. This
happens automatically depending on your driving style and the
road condi tions at the time . See
a lso => page 269, "Electronic differ ­
entia l lock ! EDU" .
Winter tires
When driving in the winter, your vehicle with All Wheel Drive has an
advantage, even with regular tires . In winter road conditions it may
be advisable to mount winter tires (or all-season tires) for improved
driveabi lity and braking: these ti res must be mounted on all four
wheel s. See
also=> page 341, "Winter tires". ~
Vehicle care Do-it-yourself service Technical data

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Tire chains
Where tire chains are mandatory on certain roads, this normally
also applies to vehicles with All Wheel
Drive:::::, page 342, "Snow
chains".
Replacing wheels/tires
Vehicles with All Wheel Drive must always have tires of the same
size . Also avoid tires with different tread depths. For details see
page :::::, page 336, "New tires and replacing tires and wheels".
Off-Road driving?
Your Audi does not have enough ground clearance to be used as an
off-road vehicle. It is therefore best to avoid rough tracks and
uneven terrain as much as possible. Also refer
to:::::, page 279.
& WARNING
Always adjust your driving to road and traffic conditions. Do not
let the extra safety afforded by All Wheel Drive tempt you into
taking extra risks.
• Although the All Wheel Drive is very effective, always
remember that braking capacity is limited by tire traction. You
should therefore not drive at excessive speeds on icy or slippery
road surfaces.
• On wet road surfaces, be careful not to drive too fast because
the front wheels could begin to slide on top of the water (aqua­ planing).
If this should occur, you will have no warning from a
sudden increase in engine speed as with a front-wheel drive
vehicle. Always drive at speeds which are suited to the road condi­
tions -risk of crash. •
Energy management
Starting ability is optimized
Energy management controls the distribution of electrical
energy and thus optimizes the availability of electrical
energy for starting the engine.
If a vehicle with a conventional energy system is not driven for a
long period of time, the battery is discharged by idling current
consumers (e.g . immobilizer) . In certain circumstances it can result
in there being insufficient energy available to start the engine.
Intelligent energy management in your vehicle handles the distribu­
tion of electrical energy. Starting ability is markedly improved and
the life of the battery is extended.
Basically, energy management consists of
battery diagnosis, idling
current management
and dynamic energy management.
Battery diagnosis
Battery diagnosis continuously determines the state of the battery.
Sensors determine battery voltage, battery current and battery
temperature. This determines the current state of charge and the
power of the battery .
Idling current management
Idling current management reduces energy consumption while the
vehicle is standing. With the ignition switched off, it controls the
energy supply to the various electrical components . Data from
battery diagnosis is considered.
Depending on the battery's state of charge, individual consumers
are gradually turned off to prevent excessive discharge of the
battery and thus maintain starting capability.
Dynamic energy management
While the vehicle is being driven , dynamic energy management
distributes the energy generated according to the needs of the indi -_,,,