Checking the Speed Sensor

Checking the Speed Sensor:




Disconnect control unit.

Measure resistance of speed sensor. It must be between 0.65 and 1.6 KOhm.

Check pulse wheel for damage, freedom of movement and eccentricity defect.

Connect oscilloscope from 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

Evenly turn wheel by hand. A sinusoidal curve should appear whose amplitude and period duration are dependent on the rotary speed. (See example in drawing.)

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*M*: Multimeter; Select multimeter on the BMW SERVICE TESTER. Select indicated multimeter function.