Audi A5 Owner's Manual page 200

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198 Intelligent technology
pedal 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.