Wheel Speed Sensor: Testing and Inspection

INSPECTION

Tone wheels can cause erratic wheel speed sensor signals. Inspect tone wheels for the following possible causes:

- missing, chipped, or broken teeth
- contact with the wheel speed sensor
- wheel speed sensor to tone wheel alignment
- wheel speed sensor to tone wheel clearance
- excessive tone wheel runout
- tone wheel loose on its mounting surface

If a front tone wheel is found to need replacement, the axle half shaft must be replaced. No attempt should be made to replace just the tone wheel. Half Shaft - Removal.

If a rear tone wheel is found to need replacement, the rear hub and bearing must be replaced. No attempt should be made to replace just the tone wheel. Rear Hub / Bearing - Removal.

If wheel speed sensor to tone wheel contact is evident, determine the cause and correct it before replacing the wheel speed sensor or the tone wheel.

Check the gap between the speed sensor head and the tone wheel to ensure it is within specifications. For wheel speed sensor air gap specifications, [1][2]Antilock Brakes / Traction Control Systems.

Excessive tone wheel runout can cause erratic wheel speed sensor signals. For tone wheel runout specifications, [1][2]Antilock Brakes / Traction Control Systems. If tone wheel runout is excessive, determine if it is caused by a defect in the axle half shaft assembly or hub and bearing. Replace as necessary.

Tone wheels are pressed onto their mounting surfaces and should not rotate independently from the mounting surface. Replace the front axle half shaft or rear hub and bearing as necessary.