Audi TT Coupe 2009 Owner's Manual page 188

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Electronic different ial lock (EOL)
The electronic differential lock monitors the rotational
speed of the drive wheels.
General notes
The electronic differential lock (EDU helps the car to start moving,
accelerate and climb a gradient on surfaces providing poor or
almost no grip. Without EDL, this would be difficult, if not impos -
sible.
How the system works
The EDL operates automatically. It monitors the rotational speed of
the drive wheels on an axle with the help of the ABS sensors
=>
page 189. If a noticeable difference in rotational speed between
the drive wheels on one axle is detected (e.g. on slippery ground on
one side), the spinning wheel is braked, thereby transferring power
to the other drive wheel or wheels (all-wheel drivel. This is done up
to a speed of about 60 mph (100 km/hl. Noises from the brake
system signal that wheel spin is being controlled.
Driving off
When driving off, always be sure to keep road conditions in mind as
you accelerate . If one drive wheel spins because it is on a surface
with less grip, gradually increase the pressure on the accelerator
pedal until the car starts to move. The wheel less able to transfer
power spins.
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 brak e 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 20. •
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
stabilization 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 189, ASR monitors the
speed of the driven wheels. If the wheels start to spin, the engine
torque 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 .
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