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Home >> Porsche >> 1987 >> 944 Base, Automatic >> Repair and Diagnosis >> Brakes >> Traction Control >> Anti-Lock Brake System >> Testing >> Program Switch Position 6 >> Wheel Speed Sensor
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Wheel Speed Sensor

  1. Raise and support vehicle. Wheel to be tested must rotate freely by hand. On drive axles, wheel not being tested must be held securely. Perform test sequence for each wheel in turn.
  2. Set wheel selection switch to wheel to be tested. Turn wheel by hand until LED displays without flickering (about one revolution per second). Read value displayed.
  3. Minimum indication is 2.0 scale divisions. There can only be a 15% difference between maximum fluctuation.
  4. If LED does not light up, check for the following: speed sensor lead incorrectly connected, speed sensor lead has open circuit, speed sensor defective or pulse gear wheel is loose or missing. Speed sensor circuit should have .8-1.8 ohms resistance.
  5. If test instrument indication is too low, check for the following: excessive air gap between speed sensor and pulse gear wheel, loose or missing pulse gear wheel, wrong gear wheel, or excessive wheel bearing play.
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