2008 AUDI A5 wheel

Airbag system 178Front airbagsDescription of front airbags
The airbag system is not a substitute for the seat belts.The front airbag for the driver is located in the padded hub of the
steering wheel ⇒page 178, fig. 187. The front airbag for the front
passenger is in the dashboard above the glove box ⇒fig. 188. The
locations of the airbags are marked with the word “AIRBAG”.
In conjunction with the three-point seat belts, the front airbags give
additional head and chest protection for the driver and front
passenger in the event of a severe frontal collision ⇒ in “Impor-
tant safety notes on the front airbag system” on page 179.
How the front airbags work
When fully inflated, the airbags reduce the risk of head or
chest injury.The airbag system is designed so that the airbags for the driver and
front passenger are triggered in a severe frontal collision.
In certain types of accident the front airbags, side airbags and one
of the head-protection airbags may be triggered together.
When the system is triggered, the airbags fill with a propellant gas
and open out in front of the driver and front passenger ⇒fig. 189.
In order to provide the desired extra protection in an accident, the
airbags have to inflate extremely rapidly (within fractions of a
second). The fully deployed airbags cushion the forwards move-
ment of the front occupants and help to reduce the risk of injury to
the head and the upper part of the body.
Special openings in the airbag allow the gas to escape at a
controlled rate to restrain the forward movement of the occupant's
head and torso. Once the impact has been absorbed, the airbag
deflates sufficiently for the front occupants to see forward.
Fig. 187 Driver's
airbag in steering
wheelFig. 188 Front
passenger's airbag in
dashboard
Fig. 189 Front airbags
in inflated condition
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Airbag system179
Controls
Safety
Driving tips
General maintenance
Self-help
Technical data
Important safety notes on the front airbag system
There are a number of safety points concerning the airbag
system which you should remember. This will help to
reduce the risk of injury in an accident.
WARNING
•
It is important for the driver and front passenger to maintain a
distance of at least 25 cm from the steering wheel or dashboard
⇒page 179, fig. 190. The airbag system will not be able to give the
required protection if you sit too close to the steering wheel or
dashboard. There is also a risk of injury if the airbags are inflated.
The front seats and head restraints must always be positioned
correctly for the height of the occupant.
•
If you do not wear a seat belt, if you lean forward or to the side,
or are not seated correctly while the vehicle is in motion, you are
at greater risk of injury. Should the airbag system be triggered in
an accident there is an even greater risk of injury.
•
Never let a child travel on the front seat without an appropriate
restraint system. If the airbag is triggered in an accident, the child
could sustain serious or fatal injuries ⇒page 185, “Child safety”.
•
Never install a rearward-facing child safety seat on the front
passenger's seat unless the front passenger's airbag has been deactivated. However, if you have no alternative but to use a rear-
ward-facing child seat on the front passenger's seat, the front
passenger's airbag must be deactivated beforehand by means of
the key-operated switch* ⇒page 183. Failure to observe this
precaution could result in serious or potentially fatal injury.
•
Occupants sitting in the front of the car must never carry any
objects or pets in the space between them and the airbags, or
allow children or other passengers to travel in this position.
•
Do not cover or stick anything on the steering wheel hub or the
soft plastic surface of the airbag unit on the passenger's side of
the dashboard, and do not obstruct or modify them in any way.
These parts should only be cleaned with a dry cloth (or with a
cloth moistened with plain water). It is also important not to
attach any objects such as cup holders or telephone mountings to
the surfaces covering the airbag units.
•
Any work on the airbag system or removal and installation of
the airbag components for other repairs (such as repairs to the
steering wheel) must be performed by a qualified workshop.Note
If necessary, you can deactivate the front passenger's airbag by
means of the key-operated switch* ⇒page 183.
Fig. 190 Minimum
distance from steering
wheel
WARNING (continued)
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Intelligent technology 196Intelligent technologyElectronic stabilisation program (ESP)General notes
The electronic stabilisation program increases the car's
stability on the road.The ESP is designed to enhance the control over the vehicle in crit-
ical handling situations, such as when accelerating and cornering.
It reduces the tendency to skid under all road conditions and
improves the stability and roadholding of the vehicle. The system
works at all speeds.The anti-lock brake system (ABS), the electronic differential lock
(EDL) and the traction control system (ASR) are all integrated into
the electronic stabilisation program.
How the system works
The ESP control unit processes data from the three integrated
systems. It also processes additional inputs provided by other high-
precision sensors. These register the vehicle's rotation about the
vertical axis (yaw rate), lateral acceleration, brake pressure and
steering wheel angle.
The system uses the steering wheel angle and road speed to calcu-
late the changes of direction intended by the driver, and constantly
compares them with the actual behaviour of the vehicle. If the
desired course is not being maintained (for instance, if the car is
starting to skid), then the ESP compensates automatically by
braking the appropriate wheel.
The forces acting on the braked wheel effectively bring the car back
to a stable condition. If the car is oversteering (rear wheels losing
grip first) the brake application is concentrated on the outside front
wheel; if the car is understeering (front wheels losing grip first), ESP
brakes the inside rear wheel. This automatic brake application is
accompanied by characteristic noises.
The ESP works in conjunction with the ABS ⇒page 197. If a
malfunction should occur in the ABS, the ESP will also be out of
action.
Switching on
The ESP is switched on automatically when the engine is started
and performs a self-test routine. As soon as this routine is complete,
the system switches back to normal operating mode. You can press
the button ⇒fig. 203 or ⇒fig. 204 to switch on the ESP or traction
control system (ASR) if they have been switched off. The message
ESP/ASR on will appear briefly in the display.
Fig. 203 Without MMI:
Centre console with
ESP switchFig. 204 Centre
console with ESP
switch
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Intelligent technology197
Controls
Safety
Driving tips
General maintenance
Self-help
Technical data Switching off
The ESP should normally be left switched on at all times. If required,
you can press the ESP OFF button to switch off the traction control
system (ASR) or the electronic stabilisation program (ESP).
•
Switching off the traction control system (ASR): Press the ESP
button briefly. The traction control system (ASR) can be switched off
in special driving conditions, e.g. if you are driving with snow chains
⇒page 198. The message ASR off will appear in the display.
•
Switching off the ESP/traction control system (ASR): Press the
ESP button for longer than 3 seconds. The ESP/ASR warning lamp
lights up when the system is switched off, see ⇒page 16. The
message ESP switched off will appear in the display.
WARNING
•
The ESP is not able to overcome the physical limits of adhesion.
Even with ESP, you should always adjust your speed to suit the
conditions. Please bear this in mind, especially on wet or slippery
road surfaces. Do not let the extra safety provided tempt you into
taking any risks when driving – this can cause accidents.
•
Please note that, when the ESP or ESP/traction control system
(ASR) is switched off, the driven wheels may start to spin, causing
the vehicle to lose grip, in particular on slippery or wet roads -
danger of skidding!
Anti-lock brake system (ABS)
ABS prevents the wheels from locking up under braking.The anti-lock brake system (ABS) is an important part of the car's
active safety system. However, the ABS will not necessarily guar-
antee shorter stopping distances in all conditions. For instance, on
loose gravel or fresh snow on top of an icy surface (conditions which
anyway require extreme care and reduced speed), the stopping
distance with ABS may even be slightly longer.How the ABS works
The system runs an automatic self-check when the car reaches a
road speed of about 6 km/h. This may be accompanied by a noise
from the ABS pump.
If one of the wheels is turning too slowly in relation to the road
speed, and is close to locking up, the system will reduce the pres-
sure in the brake line to this wheel. The driver is made aware of this
control process by a pulsating of the brake pedal and accompa-
nying noise. This is a deliberate warning to the driver that one or
more of the wheels is tending to lock up and the ABS control func-
tion has intervened. In this situation it is important to keep the brake
pedal fully depressed so the ABS can regulate the brake application
- do not “pump” the brake pedal.
WARNING
The grip provided by ABS is still subject to the physical limits of
adhesion. Always bear this in mind, especially on wet or slippery
roads. If you notice that the ABS is working (to counteract locked
wheels under braking), you should reduce speed immediately to
suit the road and traffic conditions. Do not let the extra safety
provided tempt you into taking any risks when driving – this can
cause accidents.
Note
If a malfunction should occur in the ABS, this is indicated by a
warning lamp ⇒page 18.Brake assist system
The brake assist system helps the driver to achieve
optimum braking effect.The brake assist system helps to increase braking power and thus to
achieve a shorter stopping distance. If the driver presses the brake
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Intelligent technology 198pedal very quickly, the brake assist system automatically 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 assist system
switches itself off as soon as you release the brake pedal.
The brake assist system will not be operative if there is a malfunc-
tion in the 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 too close behind the vehicle in front of you. An increased
accident risk cannot be compensated even by the brake assist
system, so always be sure to maintain a safe speed.Traction control system (ASR)
The traction control system prevents the driven wheels
from spinning when the car is accelerating.General notes
The traction control system (ASR) is one of the functions incorpo-
rated in the electronic stabilisation program (ESP).
The traction control system (ASR) helps the car to start moving,
accelerate and climb a gradient in slippery conditions where this
may otherwise be difficult or even impossible.
How the system works
The ASR acts automatically i.e. without the driver's intervention.
With the aid of the ABS sensors ⇒page 197, the ASR monitors the
speed of the driven wheels. If the wheels start to spin, the engine
power is reduced automatically to match the amount of grip avail-
able. The system works at all speeds.The ASR works in conjunction with the ABS. If a malfunction should
occur in the ABS, the ASR will also be out of action.
Switching on
The ESP is switched on automatically when the engine is started
and performs a self-test routine. As soon as this routine is complete,
the system switches back to normal operating mode. If the traction
control system (ASR) has been deactivated (for one of the reasons
noted below) you can switch it back on manually by pressing the
switch ⇒page 196, fig. 203. The message ESP/ASR on will appear
briefly in the display. If the traction control system (ASR) has been
deactivated, it will switch back on automatically at a speed of about
70 km/h on vehicles with front-wheel drive.
You can switch the traction control system (ASR) on again if neces-
sary by pressing the switch ⇒page 196, fig. 203.
Switching off
If required, the ASR can also be switched off manually by pressing
the switch briefly ⇒page 196, fig. 203 (for less than 3 seconds). The
ESP warning lamp lights up when the traction control system (ASR)
is switched off, see ⇒page 16. The message ASR off will appear in
the display. For safety reasons, the system can only be switched off
at speeds below 50 km/h on vehicles with front-wheel drive. The
ASR can be deactivated at any speed on vehicles with four-wheel
drive.
The traction control system should normally remain switched on at
all times. It should only be switched off manually in particular
circumstances where a certain amount of wheel slip may be desir-
able. For example:
•
when driving with snow chains
•
when driving in deep snow or on loose surfaces
•
when rocking the car backwards and forwards to free it.
The ASR should be switched on again afterwards as soon as
possible.
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Intelligent technology199
Controls
Safety
Driving tips
General maintenance
Self-help
Technical data
Note
To ensure that the ASR works properly, all four wheels must be fitted
with identical tyres. Any differences in the rolling radius of the tyres
can cause the system to reduce engine power when this is not
desired. Also refer to ⇒page 245, “Replacing wheels and tyres”.Electronic differential lock (EDL)
The electronic differential lock monitors the speed of the
driven wheels.General notes
The electronic differential lock (EDL) helps the car to start moving,
accelerate and climb a gradient in slippery conditions where this
may otherwise be difficult or even impossible.
How the system works
The EDL acts automatically. With the aid of the ABS sensors
⇒page 197, the system monitors the rotational speed of the driven
wheels on each axle. Whenever it detects a significant difference in
the speed of the driven wheels of one axle (for example, if the road is
slippery on one side) the system applies the brake to slow down the
spinning wheel so that more of the power is directed to the other
wheel of this axle (or to the three other wheels on vehicles with four-
wheel drive). This function is active up to about 100 km/h. The brake
system will make noises while it is working.
Driving away from a standstill
Sometimes one wheel has less grip and starts spinning, for
example, if one of the driven wheels is on ice. In this case, keep
pressing the accelerator gradually until the car starts moving, even
though the wheel with less grip will still spin.
Overheating of the brakes
To prevent the disc brake of the braked wheel from overheating, the
EDL cuts out automatically if subjected to excessive loads. The car remains operational and will behave in the same way as a car
without EDL.
The EDL will switch on again automatically when the brake has
cooled down.
WARNING
•
When accelerating on a uniformly slippery surface (for instance
all four wheels on ice or snow), press the accelerator gradually and
carefully. The driven wheels may otherwise start to spin (in spite
of the EDL), which would impair the car's stability and could lead
to an accident.
•
Even with EDL, you should always adjust your speed to suit the
conditions. Do not let the extra safety provided tempt you into
taking any risks when driving – this can cause accidents.Note
If the ABS warning lamp lights up, this can also mean there is a fault
in the EDL. Please contact a qualified workshop as soon as
possible.BrakesNew brake pads
New brake pads do not give full braking effect for the first 400 km,
they must first be “bedded in”. However, you can compensate for
the slightly reduced braking effect by applying more pressure on
the brake pedal. Avoid placing a heavy load on the brakes during the
running-in period.
We ar
The rate of wear on the brake pads depends a great deal on how you
drive and the conditions in which the vehicle is operated. Negative
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Intelligent technology 200factors are, for instance, city traffic, frequent short trips or hard
driving with abrupt starts and stops.
Wet roads; road salt
When you are driving at a speed higher than 80 km/h and have the
windscreen wipers switched on the brake pads are very briefly
brought into contact with the brake discs. This automatic process
which goes unnoticed by the driver is carried out at regular intervals
and is intended to improve braking response in wet conditions.
In certain conditions, such as in heavy rain, or after washing the car
or driving through water, the full braking effect can be delayed by
moisture (or in winter by ice) on the discs and brake pads. The
brakes should be “dried” by pressing the pedal to restore full
braking effect.
The effectiveness of the brakes can also be temporarily reduced if
the car is driven for some distance without using the brakes when
there is a lot of salt on the road in winter. The layer of salt that accu-
mulates on the discs and pads can be removed with a few cautious
brake applications.
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 used infrequently, or if
you only drive low mileages without using the brakes very much.
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 the brake pedal travel should ever increase suddenly, this may
mean that one of the two brake circuits has failed. Drive immedi-
ately to the nearest qualified workshop and have the fault rectified.
On the way to the dealer, be prepared to use more pressure on the
brake pedal and allow for longer stopping distances.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.
Brake servo
The brake servo amplifies the pressure you apply to the brake pedal.
It only works when the engine is running.
WARNING
•
When applying the brakes to clean off deposits on the pads and
discs, select a clear, dry road. Be sure not to inconvenience or
endanger other road users; do not risk an accident.
•
Never let the car coast with the engine switched off (this can
cause accidents).Caution
•
Never let the brakes “drag” by leaving your foot on the pedal
when you do not really intend to brake. This overheats the brakes,
resulting in longer stopping distances and greater wear.
•
Before driving down a long, steep gradient, it is advisable to
reduce speed and move the selector lever to a lower gear. In this
way you will make use of the engine braking effect and relieve the
load on the brakes. If you still have to use the brakes, it is better to
brake firmly at intervals than to apply the brakes continuously.Note
•
If the brake servo is out of action due to a malfunction, or if the
car has to be towed, you will have to press the brake pedal consid-
erably harder to make up for the lack of servo assistance.
•
If you wish to equip the car with accessories such as a front
spoiler or wheel covers, it is important that the flow of air to the
front wheels is not obstructed, otherwise the brakes can overheat.
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Intelligent technology201
Controls
Safety
Driving tips
General maintenance
Self-help
Technical data
Power steering (servotronic)The power steering assists the driver when turning the
steering wheel (with the engine running).The power steering assists the driver by reducing the force needed
to turn the steering wheel. The degree of power assistance is
adapted electronically, depending on the speed.
If a fault should occur in the servotronic system the power steering
will still operate. The degree of power assistance will, however, no
longer adapt to different speeds. If the electronic regulating system
is not working properly, this is most noticeable when turning the
steering wheel at low speeds (for instance when parking) – more
effort will be required than usual. The fault should be corrected by
a qualified workshop as soon as possible.
The power steering does not function when the engine is switched
off. In this case the steering wheel is very hard to turn.
If the steering is held at its turning limit when the car is stationary,
this will place an excessive load on the power steering system. In
this case, the power steering system will make noises. It will also
reduce the idling speed of the engine.
Caution
Do not keep the steering in the full-lock position for longer than
15 seconds when the engine is running – this could cause damage
to the power steering system.
Note
•
If the power steering should fail at any time or the engine is
switched off (for instance when being towed), the car can still be
steered. However, more effort will be required to turn the steering
wheel.
•
If the system is leaking or malfunctioning, please take the car to
a qualified workshop as soon as possible.
•
The power steering requires a special hydraulic fluid. The fluid
reservoir is located at the front of the engine compartment on the
left ⇒page 232. The correct fluid level in the reservoir is important
for the power steering to function properly. The hydraulic fluid level
is checked at the Inspection Service.
Applies to vehicles: with four-wheel driveFour-wheel drive (quattro
®)
On quattro models the engine power is distributed to all
four wheelsGeneral notes
On four-wheel drive vehicles, the engine power is distributed to all
four wheels. The distribution of power is controlled automatically
according to your driving style and the road conditions. Also refer
to ⇒page 199, “Electronic differential lock (EDL)”.
The four-wheel drive is specially designed to complement the supe-
rior engine power of your Audi. This combination gives the car
exceptional handling and performance capabilities – both on
normal roads and in more difficult conditions, such as snow and ice.
Even so (or perhaps especially for this reason), it is important to
observe certain safety points ⇒.
Winter tyres
Thanks to its four-wheel drive, your car will have plenty of traction
in winter conditions, even with the standard tyres. Nevertheless, we
still recommend that winter tyres or all-season tyres should be fitted
on all four wheels when winter road conditions are expected, mainly
because this will give a better braking response.
Snow chains
On roads where snow chains are mandatory, this also applies to cars
with four-wheel drive ⇒page 248, “Snow chains”.
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