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Wheel-speed signal output

Wheel-speed signal output

Several other systems in the car must be aware of the vehicle speed. The TC/ABS control module, which is connected to the P-bus, provides information on the speed of all the wheels. The speed is based on a wheel with a circumference of 200 cm.

Information on the wheel speed is converted into vehicle speed in km/h (mph) in the main instrument unit. The speed is corrected depending on the programmed tyre size. The speed information is then sent on the I-bus.

Pin 23 is used as an output for information on wheel speed for other systems that cannot handle bus information.

The engine management system is connected to the P-bus and therefore has access to the same speed information.


Speed information can also be sent even if the warning lamps for ABS, brake fluid, central warning or TCS OFF are on. The information is sent as long as one of the rear wheel sensors is working.

For more information on wheel speed on the bus, see Electrical system, Bus and diagnostic communication, System overview and Main Instrument Unit, System overview .

Diagnostics

If the wheel-speed signal output is faulty, a DTC will be set in the receiving system.