2008 AUDI A5 ABS

Driving123
Controls
Safety
Driving tips
General maintenance
Self-help
Technical data braking force of the parking brake is only released when there is
enough power at the wheels to make the vehicle move in the desired
direction.
Note
For safety reasons the parking brake will only release automatically
if the driver's seat belt is engaged in its buckle.Driving away when towing a trailer
Please note the following points to prevent the vehicle
from rolling back unintentionally on a gradient.– Pull and hold the parking brake switch and press the
accelerator. The parking brake will remain engaged and
prevent any tendency to roll back down the slope.
– You can release the parking brake switch as soon as the
engine is delivering enough power to the wheels.Depending on the weight of the vehicle and trailer and the steep-
ness of the slope, there may be a tendency to roll back downhill
when driving away from a standstill. You can prevent this by pulling
out the parking brake switch as you press the accelerator (in the
same way as with a conventional handbrake).Emergency braking function
This feature enables you to stop the vehicle if the main
brake system should fail or if the pedal is obstructed.– Pull out and hold the parking brake switch to stop the
vehicle with the parking brake in an emergency.
– The brakes will be released immediately if you release the
switch or press down the accelerator.
If you pull out and hold the parking brake switch at a road speed
above about 8 km/h, this will initiate an emergency brake applica-
tion. The brakes are then applied hydraulically at all four wheels.
The effect is the same as an emergency stop (full brake application)
⇒
To prevent the emergency braking function from being used acci-
dentally, a warning buzzer sounds when the switch is operated. The
brakes are released immediately when you release the switch or
press down the accelerator.
WARNING
You should only use the emergency braking function in a real
emergency, for example if the brake system should fail or if the
brake pedal is obstructed. If you use the emergency braking func-
tion by activating the parking brake switch, the effect is similar to
a full brake application (emergency stop). Please remember that
the ESP (with its combined ABS, EDL and traction control func-
tions) is still subject to certain physical limits. In a corner or in bad
road or weather conditions an emergency stop can cause the
vehicle to skid or lose steering control.Driver messages in the instrument cluster displayCaution: Vehicle parked too steep
This message can appear when you apply the parking brake if the
car is parked on a gradient steeper than about 30%.
In this case the parking brake may not be strong enough to prevent
the vehicle from rolling back accidentally.
Please release parking brake
However, please remember that, for safety reasons, the parking
brake will only release automatically if the driver's seat belt is
buckled.
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Seat belts 170Seat beltsWhy is it so important to use seat
belts?Seat belts provide effective protection
The common belief that passengers can brace their
weight with their hands in a minor collision is false.It is an established fact that seat belts provide good protection in
accidents. Therefore wearing a seat belt is required by law in most
countries.
Properly worn seat belts hold the occupants in the best position for
maximum protection ⇒fig. 177. The seat belts are capable of
absorbing much of the kinetic energy arising in a collision. Also they
help to prevent uncontrolled movements which could lead to severe
injuries ⇒page 171, “Important safety instructions for using seat
belts”.
If they wear the seat belts correctly, the passengers benefit greatly
from the ability of the belts to reduce the kinetic energy gradually.
The front crumple zones and other passive safety features (such as
the airbag system) are also designed to absorb the kinetic energy
generated in a collision. Taken together, all these features reduce the forces acting on the occupants and consequently the risk of
injury.
Although these examples are based on a frontal collision, the phys-
ical principles involved are the same in other types of accidents and
for vehicles with an airbag system. This is why it is so important to
put on the seat belts before every trip – even when “just driving
around the corner”. Ensure that your passengers wear their seat
belts as well ⇒.
Properly worn seat belts have been shown to be an effective means
of reducing the potential for injury and improving the chances of
survival in a serious accident ⇒page 171, “Forces acting in a colli-
sion”.
For information on how children can travel safely in the car
⇒page 185, “Points to remember if children are travelling in the
car”.
WARNING
•
Seat belts must be put on before every trip – even when driving
in town. This also applies to the rear passengers (injury risk).
•
During pregnancy, women should always ensure they wear a
seat belt. The best way to protect the unborn child is to protect the
mother ⇒page 174, “Wearing and adjusting the seat belts during
pregnancy”.
Fig. 177 Driver
protected by the prop-
erly worn seat belt
during a sudden brake
manoeuvre
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Seat belts171
Controls
Safety
Driving tips
General maintenance
Self-help
Technical data
Important safety instructions for using seat belts
There are a number of safety points concerning the seat
belts which you should remember. This will help to reduce
the risk of injury in an accident.
WARNING
•
The seat belts can only provide maximum protection if the
seats are adjusted properly ⇒page 70, “Seats and storage”.
•
To ensure proper protection, it is important to wear the seat
belts in the correct position ⇒page 173, “How to wear seat belts
properly”. Ensure that the seat belts are worn exactly as recom-
mended in this chapter. Belts which are not worn properly can
increase the risk of injury in accidents considerably.
•
Do not allow the seat belt to become twisted or jammed, or to
rub on any sharp edges.
•
Never allow two passengers (even children) to share the same
seat belt. It is especially dangerous to place a seat belt over a child
sitting on your lap.
•
Do not wear the belt over hard or fragile objects (such as
glasses or pens, etc.) because this can cause injuries.
•
Loose, bulky clothing (such as an overcoat over a jacket)
impairs the proper fit and function of the belts.
•
The belts must be kept clean, otherwise the retractors may not
work properly ⇒page 226, “Seat belts”.
•
The slot in the seat belt buckle must not be blocked with paper
or other objects, as this can prevent the latch plate from engaging
properly.
•
The latch plate of the belt must always be engaged in the
correct buckle for that seat, otherwise the belt will not be fully
effective.
•
Check the condition of the seat belts at regular intervals. If you
notice that the belt webbing, fittings, retractor mechanism or buckle of any of the belts is damaged, the belt must be replaced
by a qualified workshop.
•
The seat belts must not be removed or modified in any way. Do
not attempt to repair a damaged belt yourself.
•
Seat belts which have been worn in an accident and stretched
must be replaced by a qualified workshop. The belt anchorages
should also be checked.
Forces acting in a collisionThe physical principles involved in a frontal impact
Very large forces are generated during a collision; these
forces have to be absorbed.
WARNING (continued)
Fig. 178 Passengers of
a vehicle which is
headed for a brick wall.
They are not using seat
belts.
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Seat belts 172The physical principles involved in a frontal collision are relatively
simple:
Both the moving vehicle and the passengers possess energy, which
is known as “kinetic energy” ⇒page 171, fig. 178. The amount of
“kinetic energy” depends on the speed of the vehicle and the weight
of the vehicle and passengers. The higher the speed and the greater
the weight, the more energy there is to be absorbed in an accident.
The most significant factor, however, is the speed of the vehicle. If
the speed doubles from 25 km/h to 50 km/h, for example, the kinetic
energy increases by a factor of four. Because these passengers are
not restrained by seat belts, the entire amount of kinetic energy has
to be absorbed at the point of impact ⇒fig. 179. This would result
in serious or potentially fatal injury.
Even at urban speeds of 30 km/h to 50 km/h, the forces acting on the
occupants in a collision can reach the equivalent of 1 ton (1000 kg)
or more. At greater speed these forces are even higher. A rule of
thumb: if the speed doubles, the forces increase by a factor of four.
Passengers who do not wear seat belts are not “attached” to the
vehicle. In a frontal collision they will continue to move forward at
the speed their car was travelling just before the impact.
What happens to passengers not wearing seat belts?
Passengers not wearing seat belts risk fatal injuries in the
event of an accident.In a frontal collision, unbelted passengers will be thrown forwards
and make violent contact with the steering wheel, dashboard, wind-
screen, etc ⇒fig. 180. Passengers not wearing their belts risk being
thrown out of the car, resulting in potentially fatal injuries.
The common belief that occupants can brace their weight with their
hands in a minor collision is false. Even at low speeds the forces
acting on the body in a collision are so great that it is not possible
to hold yourself in the seat.
Fig. 179 The vehicle
crashes against the
wall
Fig. 180 A driver not
wearing a seat belt can
be thrown forwardsFig. 181 A rear
passenger not wearing
a seat belt can be
thrown forwards
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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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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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