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Wheel-speed signal output

Wheel-speed signal output

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

This information is converted in the MIU to vehicle speed in km/h (mph). This speed is adjusted depending on the size of the tires. This vehicle speed information is then sent out over the I-bus.

Wheel speed information is sent to systems that cannot handle bus information via pin 23.

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



Speed information can be sent even when the ABS, brakes, TCS OFF or central warning lamps 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.