2011 AUDI S8 wheel

Knee airbags
Description of knee airbags
The knee airbag system can provide supple ­
mental protection to properly restrained
front seat occupants.
Fi g. 1 52 Driver's a irbag
The drive r knee airbag is in the instr ume nt
panel underneath the steeri ng wheel
¢ fig . 152, th e ai rbag for the passenger is at
about the same height in the instrument pan ­
e l underneath the g love compartment.
The knee a irbag offers add itiona l pro tect io n
to the driver's and passenger 's knees and up­
per and lower thigh areas as a supp lements
the protect ion provided by the safety belts.
If the front airbags deploy, the knee airbags
a lso deploy in frontal collisions when the de­
p loyment thresho ld stored in the contro l unit
is met
r::!;> page 154, More important things to
know about front airbags.
In addition to t heir normal safety function,
safety be lts he lp keep the driver or front pas­
se nger in posit ion in a frontal coll is ion so that
the airbags ca n prov ide supplemental protec­
tion .
T he airbag system is not a s ubst itute for yo ur
safety be lt. Rather, it is part of the overall oc­
cupa nt restraint system in your veh icle. Al­
ways remember that the airbag system ca n
only help to pro tect you if you are wea ring
your safety belt and wear ing it prope rly. Thi s
i s w hy you sho uld always wea r yo ur safety
be lt, not just because the law requires yo u to
do so
¢ page 137, General notes .
Airbag system 161
The safety belt buckle fo r the driver a nd front
seat passe nger have switches that tell the air­
bag control module if th e safety belt is being
u sed or not . If the safety belt is being used,
the knee airbag w ill deploy at a s light ly higher
rate of deceleration t han if t he be lt is not be ­
i ng used. Therefore, in a pa rticular co llision, it
is possible that an airbag will not dep loy at a
seat ing pos ition w he re t he safety be lt is being
u sed b ut w ill infl ate a t the po sition where the
safety belt is no t being used.
Remember too, a irbags wi ll deploy o nly once
and on ly in certa in kin ds of ac ciden ts -yo ur
sa fe ty belts a re a lw ay s there t o offer p rotec ­
t ion in those accide nts in which airbags are
not supposed to dep loy o r when they have al ­
ready dep loyed, for example when your vehi­
cle strikes or is struck by another after the
first collision.
This is just one of the reasons why an airbag is
not a s ubstitute fo r th e safety be lt . T he airbag
system works most effect ively when used with
the safety be lts. Therefore, always wea r your
safety belts correct ly.
It is important to remember that while the
supplementa l knee airbag system is designed
to reduce the li kelihood of ser ious injuries ,
other injur ies, for example, swelling, bru is ing,
minor abras ions and frict ion bu rns can a lso
occur when an airbag in flates.
The knee airbag system basically consists
of:
- The electronic control module
- Two inflatable a irbags (a irbag an d gas gen-
erator), one for the d river and one fo r the
front passenge r
- The a irbag indicator lig ht in t he i nstrument
pane l
The knee airbag system will not deploy :
-when the ignit io n is switched off
- in frontal collisions when the de celera tion
meas ured by the contro l unit is too low
- in side co llisions
- in rear-end col lis ions
- in rollove rs

162 Airbag system
-in the event of a system malfunction (warn­
ing/indicator light is on)
r=:> page 18.
.&_ WARNING
-Safety belts and the airbag system can
only provide protection when occupants
are in the proper seating position
¢page 154 .
-If the airbag indicator light comes when
the vehicle is being used, have the sys­
tem inspected immediately by your au­
thorized Audi dealer.
How knee airbags work
The risk of injury to the leg area can be re­
duced by fully inflated knee airbags.
Fig. 153 Infla ted airbags pro tecting in a fron ta l coll i­
sio n
The knee airbag system has been designed so
that the airbags for the driver and front pas­
senger deploy in certain but not all frontal
collisions .
If the front ai rbags deploy, the knee ai rbags
also deploy in frontal collisions when the de­
ployment threshold stored in the control unit
is met .
When the system deploys, the ai rbags fill
with a propellant gas, and inflate between the lower part of the instrument panel and the
driver and the lower part of the instrument
panel and the front passenger~
page 154,
fig. 150.
Although they are not a soft pillow, they can
"cushion" the impact and in this way they can
help to reduce the risk of injury to the lower
extremities . All of this takes place in the blink of an eye, so
fast that many people don
't even realize that
the airbags have deployed. The airbags also inflate with a great deal of force and it is im­
portant for occupant safety that nothing
should be in their way when they deploy .
Fully inflated airbags in combination with
properly worn safety belts slow down and lim­
it the occupant's forward movement and help
to reduce the risk of injury .
Important safety instructions on the
knee airbag system
Airbags are only supplemental restraints . Al­
ways wear safety belts correctly and ride in a
proper seating position .
There is a lot that you and your passengers
must know and do to help the safety belts and
airbags to provide supplemental protection .
.&_ 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 knee airbag system cannot protect
you properly if you are seated too close
to any of the airbag locations. When ad­
justing their seat positions, it is impor­
tant that both the driver and the front passenger keep their upper bodies and
knees at the following minimum safe
distances:
- at least 10 inches (25 cm) between the
chest and the steering wheel/instru­ ment panel.
- at least 4 inches (10 cm) between the
knees and the lower part of the instru­
ment 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 in­
creases even more should the airbag de­
ploy .

170 Child Safety
-Always install rear-facing child safety
seats on the rear seat.
-If you must install a rearward facing
child safety seat on the front passenger
seat in exceptiona l circumstances and
the
PASSENGER AIR BAG OFF light does
not come on and stay on, immed iately
install the rear-facing child safety seat in
a re ar seating posit ion and have the air­
bag system inspec ted immediately by
yo ur Audi dealer.
_& WARNING
If, in exceptional circumstances, you must
install a forward -facing child restraint on
the front passenger's seat:
- Always make su re the forward-fac ing
seat has been designed and certified by
its manufacturer for use on a front seat
with a passenger front and side airbag.
- Always follow the man ufacturer's in­
struct ions provided with the child safety
seat or carrier.
- Always move the passenger seat into its
rearmost position in the seat 's fore and
aft adjustment range, as far away from
the a irbag as poss ible before installing
the ch ild restraint. The backrest must be
adjusted to an upr ight position .
- Always make sure that the
PASSENGER
AIR BAG OFF
light comes on and stays
on all the time whenever the ignition is
switched on.
Advanced front airbag system and
children
Your vehicle is equipped with a front "Ad ­
vanced A irbag System" in compliance wit h
United States Federal Motor Vehicle Safety
Standard (FMVSS) 208 as app licab le at the
time your veh icle was manufactured.
The Advanced Airbag system in your vehicle
has been certified to meet the " low-risk" re­
qu irements for 3- and 6-year old ch ildren on
the passenger s ide and small adults on the
driver side . The low risk deployment criter ia are intended
to red uce the risk of in jury
thro ugh interaction with the airbag that can
occur, for examp le, by being too close to the
steering wheel and instrument panel when
the a irbag inflates. In addition, the system
has been certified to comply with the "sup ­
pression" requirements of the Safety Stand­
ard, to turn off the front a irbag for infants up
to 12 months who are restrained on the front
passenge r seat in child restra ints that are list­
ed in the Standard .
Even though your veh icle is equipped with an
Advanced Airbag system, a ll children, espe­
cially those 12 years and younger, should al­
ways ride in the back seat properly res trained
for their age and size . The airbag on the pas­
senger side makes the front seat a potentially
dangerous place for a ch ild to ride . The front
seat is not the safest p lace for a child in a for­
ward-fac ing ch ild safety seat. It can be a very
dangerous place for an infant or a larger child
in a rearward-fac ing seat .
Advanced Airbags and the weight­
sensing mat in the front seat
The Advanced Airbag System in you r vehicle
detects the presence of an infant or child in a
child restraint on the front passenger seat us ­
ing the weight-sens ing mat in the seat cush­
ion and the sensor below the safety belt latch
on the front passenger seat that measures the
tens ion on the safety belt .
The weight-sensing mat measures total
weight of the child and the child safety seat and a ch ild blanket on the front passenger
seat. The we ight on the front passenger seat
is related to the design of the ch ild restraint
and its "footp rint", the s ize and shape of the
bottom of the child res traint as it sit s on the
seat. The weight of a ch ild restra int and its
"footprint" vary for different kinds of child re­
straints and for the different mode ls of the
same kind of chi ld restraint offered by ch ild
restraint manufacturers.
T he weight ranges fo r the individual types,
makes and models of child restraints that the .,._

190 Intelligent technology
Intelligent technology Notice about data
recorded by vehicle
control modules
Your veh icle is not equipped with an Event Da­
ta Recorder (EDR), installed by some manu­
facture rs for the express purpose of capturing
data for retrieval after an accident or crash
event . EDR's are sometimes ca lled "crash re­
corders".
Some state laws restrict the retr ieval or down­
loading of data stored by EDR's that were in­
stalled in a vehicle for the express purpose of
retrieving data after an accident or crash
event without the owner's consent.
A lthough your vehicle is not equipped with an
EDR, it is equipped with a number of electron­
ic control modules for various vehicle systems
such as, for example, eng ine function, em is­
sion control, as well as for the airbags and
safety belts.
These electronic contro l modules also record
vehicle-re lated data during normal vehicle op­
eration for diagnostic and repair purposes.
The recording capacity of the electronic con­
trol modules is limited to data (no sound is re­
corded) and only a small amount of data is ac­
tually recorded over a ve ry limited pe riod of
time and stored when a system fault or other
cond ition is sensed by a control unit. Some of
the data then stored may re late to vehicle
speed, direction, braking as we ll as restraint
system use and performance in the event of a
crash or other condition. Stored data can only
be read and downloaded with special equip­
ment.
Electronic stabilization
program (ESP)
Description
ESP helps to improve road holding and vehicle
dynamics to help reduce the probability of
skidd ing and loss of veh icle control. It works
only when the engine is running. ESP detects certain difficult driving situat
ions, including
when the vehicle is beginning to spin (yaw) out of control and helps you to get the veh icle
back under control by se lectively braking the
wheels, and/or reducing engine power and
providing steer ing assistance to help hold the
vehicle on the driver's intended course. The in­
dicator light
liJ in the instrument cluster
blinks when ESP is taking action to help you
control the vehicle.
ESP has limitations.
It is important to remem­
ber that ESP cannot overcome the laws of
physics. It will not always be able to help out
under all conditions you may come up against.
For example, ESP may not always be able to
help you master situations where there is a
sudden change in the coefficient of friction of
the road surface. When there is a section of dry road that is suddenly covered w ith water,
slush or snow, ESP cannot perform the same
way it wou ld on the dry surface . If the vehicle
hydroplanes (rides on a cushion of water in­
stead of the road surface), ESP will not be
able to help you steer the vehicle because con­
tact with the pavement has been interrupted
and the vehicle cannot be braked or steered.
During fast cornering, particularly on winding
roads, ESP cannot always deal as effectively
with difficult driving situations than at lower
speeds. When towing a trailer, ESP is not able
to help you regain control as it would if you
were not tow ing a trailer.
Always adjust your speed and driving style to road, traffic; and weather condit ions. ESP can­
not override the vehicle's physical limits, in­
crease the available traction, or keep a ve hicle
on the road if road departure is a result of
driver inattention. Instead, ESP improves the
poss ibility of keeping the vehicle unde r con­
trol and on the road during extreme maneu­
vers by using the driver's steering inputs to
help keep the vehicle going in the intended di­
rection . If you are traveling at a speed that
causes you to run off the road before ESP can
provide any assistance, you may not experi­
ence the benefits of ESP .

ESP includes and/or works together with the
anti-lock brake assist system (ABS), brake as­
sist system, anti -slip regulation (ASR), elec­
tronic differential lock (EDL), dynamic steer­
ing* and electronic interaxle differential lock*.
ESP is switched on all the t ime . In certa in sit­
uations when you need less traction, you can
sw itch
off ASR by pressing the button above
the selector lever. Be sure to switch ASR on
again when you no longer need less traction.
Anti-lock braking system (ABS)
ABS prevents the wheels from locking up
when braking. The vehicle can still be steered even during hard braking . Apply steady pres­
sure to the brake pedal. Do not pump the ped­
al. A puls ing in the brake pedal indicates that
the system is he lping you to brake the vehicle.
Brake assist system
The brake assist system can decrease brak ing
distance.
It increases braking power when the
driver presses the brake pedal quickly in emer­
gency situations. You must press and hold the
brake pedal until the situation is over. In vehi­
cles with adaptive cruise control*, the brake
assist system is more sensitive if the distance
detected to the vehicle ahead is too small.
Anti-slip regulation (ASR)
ASR reduces engine power when the drive
wheels begin to spin and adapts the force to
the road conditions. This makes it easier to
start, accelerate and drive up hills .
Electronic differential lock (EDL)
The EDL brakes wheels that are spinning and
transfers the drive power to the other drive
wheel or whee ls if the vehicle is equipped with
a ll whee l drive *. This function is available up
to about 75 mph (120 km/h).
I n extreme cases, EDL automatically switches
off to help keep the brake on the braked wheel
from overheating . EDL will switch on again au­
tomatically when conditions have returned to
normal.
Intelligent technology 191
Dynamic steering*
On vehicles with dynamic steering, ESP helps
stabilize the steering in certain situations.
Electronic interaxle differential lock
function*
T he electronic interaxle differential lock func­
tion activates when driving th ro ug h curves.
Braking is targeted toward the wheels on the
inside of the curve as needed. This he lps to
minimize front whee l skid, improves traction
and allows for more precise driving through
curves .
A WARNING
- ESP, ABS, ASR, EDL, dynamic steering*
a nd the electronic interaxle differential
loc k fu nction* cannot overcome the laws
of physics. This is especially impo rtant
on slippery or wet roads.
If the systems
begin acting to stabilize your vehicle, you
should immediately change yo ur speed
to match the road and traffic conditions .
Do not let the increased safety provided
by these systems tempt you to take risks.
Doing so will increase the risk of a loss of
veh icle contro l, collision and ser ious per­
sonal injur ies.
- Always adapt your speed to road, traffic
and weather conditions. The risk of los­
ing con trol of the vehicle increases when
driving too fast, espe cially through
curves and on slippery or wet roads, and
when dr iving too close to vehicles up
ahead. ESP, ABS, the brake assist system,
EDL, ASR, dynam ic steer ing* and the
electronic interaxle differentia l lock func­
tion* cannot prevent collisions.
- Always accelerate with special care on
even, smooth surfaces such as those that
are wet or covered with ice and snow.
The drive wheels can spin even with
these assistance systems that cannot al­
ways he lp to reduce the risk of loss of ve­
hicle contro l.
-
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road and the brakes are not used. Here too,
you shou ld clean off accumu lated salt coating
from brake discs and pads with a few carefu l
applications of the brake
c> ,&. .
Cor rosion
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 cor­ rosion has formed on the discs, it is advisable
to clean off the pads and discs by brak ing
f irmly a few times from a moderately high
speed
c> &, .
Fau lts in th e bra ke s ystem
If you should notice a sudden increase in
brake peda l travel, then one of the two brake
ci rcu its may have failed
c> ,&. .
Low brak e fluid l evel
Malfunct ions can occur in the brake system if
the brake fluid level is too low. The brake fluid
leve l is monitored electronically.
Brake lining w ear statu s
Brake lining wear may be checked by visual in­
spection of the condition of the brake pads
through the openings in the whee l. If neces­
sary, the wheel may be removed for this in­
spection
c> page 262, Changing a wheel .
8_ WARNING
-You should perform braking maneuvers
for the purpose of clean ing the brake
system on ly if road condit ions permit.
Other road users must not be put at r isk -
you may cause an acc ident!
- Before descending a steep grade, reduce
speed and shift transmiss ion into a lower
gear or lower driving range . Do not ride
the brakes or hold the pedal down too lo ng or too often. This cou ld cause the
brakes to get hot and dimin ish b raking
effi ciency.
Int ellig ent technolog y 193
-Do not "ride the brakes" by resting your
foot on the pedal when you do not intend
to brake. This may cause the brakes to
overheat, premature wear and increased
stopping distance .
- Under certain cl imatic and operat ing
conditions such as passing through wa­
ter, dr iv ing in heavy rain or after washing
the vehicle, the effectiveness of the
b rakes can be reduced. In winte r, ice can
accumulate on the brake pads , lin ings,
discs and drums . Carefu lly app ly brakes
for a test . Brakes will dry and ice coat­
ings wi ll be cleaned off after a few care­
fu l brake applications.
- Driving for an extended period of time on
salt-covered roads without using your
brakes can a lso affect braking efficiency.
Clean off accumu lated salt coating from
brake discs and pads with a few careful
brake applications .
- If you damage the front spoiler, or if you
install a different spoiler, be sure the air
f low to the front brakes is not obstruct­
ed. Otherw ise the brake system could
overheat reduc ing the effectiveness of
the entire brake system.
- Failure of one b rake circuit will impai r
the braking capab ility result ing in an in­
creased stopping distance. Avoid driving
the vehicle and have it towed to the near­
est A udi dealer or qualified workshop .
Brake booster
The brake booster adds extra braking power.
The brake booster works with vacuum pres­
su re which is created only whe n the engine is
runn ing
c> &, .
A WARNING
-Never let the vehicle roll to a stop with
the engine shut off.
-
- If the b rake booster is no t working, for
examp le when towing you r vehicle, or
because the brake booster has somehow
Ill>
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194 Intelligent technology
been damaged, the brake pedal must be
pressed considerably harder to make up
for the lack of booster assistance.
Servotronic ® -
advanced power
steering system
The power steering systems use the power of
the running engine to allow precise steering
with little effort .
The advanced Servotronic® power steering
system senses the road speed and e lectroni­
cally adjusts power assistance to prov ide com­
fortable and safe steering response exactly
matched to the veh icle speed.
Power steering w ill not work if the eng ine is
off . As a result, the steering whee l wi ll be hard
to turn.
The power steering fluid level is checked dur ­
ing the scheduled maintenance serv ices.
([) Note
If there is an electronic malfun ct ion, ser­
votronic
w ill still f unction like a conven ­
tional power steer ing system, providing a
constant steering support force that is no
longer proportionate to the vehicle speed.
This is most noticeab le when turning the
steer ing whee l at low speeds (for examp le
when parking), - more effo rt will be re­
qui red than usua l.
- Be aware of the different than usual
stee ring response and adjust yo ur stee r­
i ng fo rce accord ingly.
- Have the p roblem checked and set rig ht
by an Aud i deale r as soon as possib le.
(D Tips
- When the engine is runn ing, never hold
t h e steer ing whee l turned all the way to
the right or to the left for longer than 15
se conds. The power steer ing p ump w ill
ove rhe at the hydr aulic flu id if you keep
ho ld ing the steering whee l turned all the way
. This is likely to damage the power
steering system .
- If the powe r steering system sho uld fai l
entirely, o r if the engine is not runn ing
(for examp le, whi le being towed), you
w ill sti ll be able to steer the veh icle.
However,
considerably more effort will
be required to do so.
- If the power steering system sho uld
have a leak, or is not functioning proper­
ly, contact your author ized Audi dealer
immed iately.
- The power steering system requ ires a
specially fo rmu lated hydraulic fluid. The
powe r stee ring fluid reservoir is locat ed
in the engine compartment
Q page 224.
T he corre ct fl uid level i n the reservoir is
impo rta nt fo r proper fu nctioning of the
powe r stee ring .
Driving with your
quattro ®
With All Wheel Drive, all four wheels are driv­
en .
Gen eral information
With A ll W heel Drive, power is distributed to
all four wheels. This happens automatically
depending on your driving style and the road
condit ions at the time. See also
Q page 190.
With the sport different ial*, powe r distribu ­
tion to the rear wheels is variable and can be
adjusted with Audi drive select*
Q page 106 .
Winter tires
When driving in the winter, yo ur vehicle with
All Wheel D rive has an advantage, even w ith
r egular tires . In wi nter road conditions it may
be advisable to mount winter tires (or all-sea­
son tires) for improved driveability and brak­
i ng : these tires must be mo unted o n
all four
wheel s. See also q page 253, Winter tires.
Tire chains
Where tire chains are mandatory on certa in
roads, this no rma lly also app lies to veh icles
with All Wheel D rive
q page 254, Snow
chains .

Replacing wh eels/ tire s
Vehicles w ith All Wheel Dr ive must always
have tir es of the same size. Also avoid tires
with different tread depths. For details see
pag e¢
page 249 , N ew tires and replacing
tires and wheels .
Off-Road driving?
Your Aud i does not have enough ground clear­
ance to be used as an off -road vehicle. It is
therefor e best to avoid rough tracks and un ­
even terrain as much as possible . Also refer to
¢ page 198.
A WARNING
Always adjust your driving to road and traf­
fic condit ions . Do not let the extra safety
afforded by All Wheel Drive tempt you into
taking extra risks.
- Although the All Wheel Drive is very ef­
fective, always remember that braking
capacity is limited by t ire traction . Yo u
should the refore not dr ive at excessive
speeds on icy or s lippery road surfaces.
- On wet road su rfaces, be ca reful not to
dr ive too fast because the front wheels
cou ld beg in to s lide on top of the wa ter
(aquaplaning). If this sho uld occ ur, you
will have no warning from a sudden in­
crease in engine speed as with a front­
wheel drive vehicle. A lways drive at
speeds wh ich are suited to the road con­
ditions -risk of crash .
Energy management
Starting ability is optimized
Energy management controls the distribution
of electrical energy and thus optimi zes the
availability of electrical energy for starting the engine.
If a vehicle wit h a conventional energy system
i s not driven for a long period of time , the bat­
tery is discharged by idling cu rrent consumers
(e .g. immobilizer) . In certain circumstances it
can result in there being ins ufficient energy
avai lab le to start the engine.
Int ellig ent technolog y 195
Intelligent energy management in your vehi ­
cle hand les the distribution of e lectrica l ener­
gy. Start ing ability is marked ly improved and
the life of the b attery is extended.
Bas ica lly, energy management consis ts of
batte ry diagnosi s, idling cur rent m anage­
ment
and dynamic energ y management.
Battery diagnosis
Battery diagnosis continuously de termines
the state of the battery . Sensors de termine
batte ry voltage, battery current and battery
temperature . This determines the current
state of charge and the power of the batte ry .
Idling current management
Id lin g cur ren t management reduces energy
consumption while the vehicle is standing.
With the ig nition switched off, it controls the
energy supply to the various electrical compo­ nents. Data from battery diagnos is is cons id­
ered.
Depend ing on the battery's state of cha rge ,
individua l cons umers are gradually turned off
to prevent excessive discharge of the batte ry
and th us maintain starting capability .
Dynamic energy manag ement
While the ve hicle is being driven, dynamic en ­
ergy management distrib utes the energy ge n­
erated according to the needs of the individ u­
al components . It regulates consumption, so
that more electrical energy is not being used
than is being generated and ensures an opti­
mal state of charge for the battery .
@ Tips
-But even energy management cannot
negate the limits of physics. Consider
t hat the powe r and l ife of a battery are
limited.
- If start ing ability is threatened, the indi­
cator light
(•i appears ¢ page 16, c:::3
Battery.
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