ForTwo L3-1.0L (2009)
Speedometer Head: Description and Operation
GF54.30-P-3025MCU Display Speed, Function
Shown on code (K07) Speedometer (miles)
A1
Instrument cluster
A1p8
Electronic speedometer
Vehicle speed display
The electronic speedometer is used to display vehicle speed. The speedometer is driven by a stepper motor.
Measuring the vehicle speed
The instrument cluster receives from the ESP control unit (N47-5) the wheel speeds required for the computation of vehicle speed via the Controller
Area Network (data bus/CAN bus) (CAN). The tire size is taken into account when calculating the speed. Coding takes place using STAR DIAGNOSIS.
Assessment of wheel speed signals:
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The wheel speed signals are compared against each other and thus checked in terms of plausibility. If there are no significant deviations, the
vehicle speed is calculated from the rotational speed of the left front wheel.
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If the individual wheel speed signals vary substantially, the speed signals may be faulty or the vehicle may be cornering. If, by comparing the
wheel speeds on both sides of the vehicle, the instrument cluster determines that the car is cornering, the vehicle speed is calculated from the mean
value of the front wheel speeds.
^
If the comparisons indicate one or more faulty wheel speed signals, the vehicle speed is then calculated on the basis of highest wheel speed. This
also applies if an error message is received instead of a wheel speed signal.
The travel distance is determined as for the vehicle speed.
