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Intelligent technology
The traction control system (ASR) helps the car to start moving, accelerate
and climb a gradient in slippery conditions where this may otherwise be dif-
ficult or even impossible.
How it works
The ASR works automatically, i.e. without the driver's involvement. With the
aid of the ABS sensors , the ASR monitors the speed of the driven wheels
⇒ page 189. If the wheels start to spin, the engine speed is reduced auto-
matically to match the amount of grip available. The system is active across
the entire speed range.
The ASR works in conjunction with the ABS. If a failure occurs in the ABS,
the ASR will also stop working.
In general, the ASR should be left switched on at all times. It should only be
switched off manually in particular circumstances where a certain amount of
wheel slip may be desirable. Examples:
● when driving with snow chains
● when driving in deep snow or on loose surfaces
● when rocking the vehicle backwards and forwards to free it.
The ASR should be switched on again afterwards as soon as possible.
Note
To ensure that the ASR works properly, all four wheels must be fitted with
identical tyres. The difference in size of the wheels may lead to an unde-
sired reduction in engine power. Also see ⇒ page 247.
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