Tone Wheel: 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 drive shaft must be replaced. No attempt should be made to replace just the tone wheel. Refer to AXLE SHAFTS .

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. See HUB/BEARING article.

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

Excessive tone wheel runout can cause erratic wheel speed sensor signals. For tone wheel runout specifications, SPECIFICATIONS  . If tone wheel runout is excessive, determine if it is caused by a defect in the driveshaft 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 driveshaft or rear hub and bearing as necessary.