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Speed signals

Speed signals


To determine whether wheelspin occurs at any of the drive wheels, the control module obtains information on the speed of the front wheels. Since the speed of the rear wheels is used as a reference value, this information is also recevied by the control module.

The speed of each wheel is obtained from the ABS control module as follows:

Wheel

ABS control module pin

TCS control module pin

FL

17

25

FR

7

7

RL

22

24

RR

19

8



The signal is a square wave which varies periodically between approx. battery + and 0 V 29 times per wheel revolution. For a stationary wheel the voltage may be either battery+ or 0 V.

If one or more wheels are stationary at the same time as any other wheel exceeds 10 km/h, a diagnostic trouble code will be generated. Should the fault persist for longer than 20 seconds, the TCS OFF lamp will light up and the system will be rendered inoperative.

Similarly, the system will be rendered inoperative if the speed of any wheel exceeds 280 km/h.