Replacing/Checking Speed and Reference Mark Sensors

REPLACING/CHECKING SPEED AND REFERENCE MARK SENSORS





- Unscrew shield.





- Unscrew screws of speed and reference mark sensors (D and B) and pull out sensors.

Installation Note:
- Mark new reference mark sensor (B) with a piece of tape.





- Pull off plugs on speed sensor (D) and reference mark sensor (B).
- Press plug of sensor lead out of holder.

Installation Note:
- Plug marked with tape belongs to gray plug





- Pull off protective sleeve (1).
- Lift out clip (2)

Installation Note:
- Coat seals with Molykote paste..
- Keep grease and dirt off of face surface on sensors.





Testing:
- Disconnect plug.
- Connect BMW service test unit to operating instructions (M 06/22/23)
- Use universal test leads.





- Measure resistance of sensor coil (M 06) on + and - of plug.





- Connect oscilloscope (M 22/23) on + and connections of speed sensor.
- Turn engine with the starter.
- Signal shown in the figure should be displayed.
- Only the shape is important when evaluating the signal not the amplitude height.





- Check reference mark sensor in same manner.
- If oscillograph deviates, remove sensor and check for dirt (grease,burrs,dust), cleaning if necessary.
- Check reference mark, replacing pin for flywheel if necessary