Waveform Test

Start engine. Place transmission in Low or 1st gear, and drive wheels. Using an oscilloscope, check waveform pattern on each speed sensor circuit. See WHEEL SPEED SENSOR TERMINAL ID table. See Fig 1 .
If waveform is too small or non-existent, check for faulty speed sensor and incorrect sensor-to-rotor gap. If waveform amplitude fluctuates excessively, check for axle hub eccentricity and runout. Replace axle hub if necessary.
If waveform shows noise or is somehow disturbed, check for an open circuit in sensor or harness, incorrectly mounted speed sensor and damaged rotor teeth.

Fig 1: Testing Wheel Speed Sensor Waveform Oscillation

Courtesy of CHRYSLER MOTORS.