Test 03 - Dynamic Speed Sensor Test

TEST SEQUENCE
1. Connections needed:
- T-plug (4a) with adapter (A) on Antilock Brake System (ABS) wire harness (1)
- T-plug (4b) direct on ABS control unit (2)
- Connecting lead on adapter (A) to cigarette lighter, control lamp (red) lights up
2. Switch position on adapter (A) to model '3' and test step 03 (right).
3. Lift car. Turn wheels at steady speed within nominal periods (approx. 5 km/h) until 100% display appears.





Nominal Values

4. Compare the displayed actual values obtained from the test equipment with the nominal values provided above. If nominal values are not obtained, proceed with the troubleshooting procedures below as needed.

TROUBLESHOOTING
[1][2]Speed Sensor

NOTE: DF wire harness and control unit connected (note switch position at the adapter)

Front Left, Front Right, Rear Left, Rear Right
1. Periods:
Cycle time < specified value: gear turns too fast
Cycle time > specified value: gear turns too slow

a) Visual inspection - Air gap clearance between [1][2]speed sensor and pulse wheel too great, speed sensor loose, dirty, check installation.

- Check assignment of the wheel with the display.
- Firmly hold opposite-wheel at the rear axle.
- Renew [1][2]speed sensor.

2. Pulses
- Wheel rotation too irregular.
- Check teeth of pulse wheel (condition, dirt build-up).
- Check air gap clearance between [1][2]speed sensor and pulse wheel.
- Renew pulse wheel.





Oscilloscope Test
The [1][2]speed sensor pulses can also be checked individually with the BMW Service Tester Oscilloscope. Connection with universal adapter at wire harness connector X11.

Turn corresponding wheel. The curve on the oscilloscope increases as the wheel speed increases. Ensure uniformity between shafts.