Electronic speedometer, location/task/function - GF54.30-P-4000A

MODEL 129, 140 as of 1.6.96, 

163, 168, 170, 

202 as of 1.8.96, 

208 up to 31.7.99, 

210 as of 1.6.96 up to 30.6.99 

Purpose 

The electronic speedometer is used to display vehicle speed. The display takes place via a display instrument with stepper motor.

Function 

To determine the speed the instrument cluster computer uses the four wheel speed signals which it obtains from the traction systems control module via a CAN data bus. The vehicle speed is calculated by a comprehensive computing method. It is therefore only mentioned here briefly:

The individual wheel speeds are compared and thus checked for plausibility. If significant differences in individual speed signals are recognized, the speed is determined from the speed of one of the front wheels.

If the speed signals differ significantly, it may be due to defective speed signals or cornering.

If the computer identifies by means of suitable comparisons (comparison of each side) that the vehicle is cornering, the speed is determined from the mean value of the front wheel speeds. If the comparisons indicate one or more defective wheel speeds, the speed is determined from the highest wheel speed. This also applies if a fault indication is received instead of a wheel speed signal. In this case additionally an error bit is set.

If fault indications are received for all wheel speeds, the speed "0" is displayed (pointer of speed display on left end of scale).

	ABS control module		GF42.30-P-4500A
	ETS control module		GF42.35-P-4500A
	Stepper motor, location/design/function		GF54.30-P-3009A