ABS or Traction Control warning light on? Bad Wheel Speed Sensor (WSS)? In most cases the OEM harnesses are exposed to the elements and over time can rub against parts of the under carriage causing the wiring inside to fray or in some cases completely break. Other than a visual inspection of the wiring harness, a voltmeter in the ‘ohms’ setting would verify the integrity of the wire.
The following procedures verify good continuity in a circuit with a Digital Multi-Meter (DMM).
1. Set the function to the OHM (Ω) position.
2. Disconnect the harness connector of the suspect circuit.
3. Checking the circuit side going to the wheel speed sensor. This connector will have two pins, connect the DMM leads to these two pins.
4. If the DMM displays low resistance (most ABS sensors measure 1.28-1.92 K ohms) the circuit is good, and more diagnostic tests need to be done.
IF THERE IS NO CONTINUITY (CONNECTION RESISTANCE) THE CIRCUIT IS FAULTY, AND NEEDS TO BE REPLACED
How does the ABS sensor or Wheel Speed Sensor work? As the wheel spins, the wheel speed sensor produces a AC signal. The EBCM (Electronic Brake Control Module) uses this AC signal to calculate wheel speed. Other points of interest for a faulty ABS sensor circuit would be to inspect the tone ring and plug connections.