Speed Sensor Check

- Disconnect control unit.

- Measure resistance of the speed sensor. It must be between 1.04 and 1.16K Ohms.

- Check pulse wheel for damage, ease of movement and eccentricity faults.

- Check clearance (air gap) and set if necessary:

Nominal value front 0.27...1.24 mm
Nominal value rear 0.48... 1.23 mm

- Connect oscilloscope of BMW Service Tester as follows:

Terminal D+ blue to speed sensor signal.
Frequency (-) black to speed sensor ground.
Frequency (+) blue to terminal 1 black.

*M* 13 Select frequency and enter 80 Hz

*M* 22 Select oscilloscope

- Uniformly turn wheel by hand. A sinusoidal curve must be displayed whose amplitude and period duration change dependent on the rotary speed.