BRAKE TECH: ABS Wheel Speed Sensor Tone Ring Problems

I have been working on a lot for cars with ABS lately with wheel speed sensor (WSS) problem. Codes “erratic” signals from wheel speed sensors seem to be a lot more common. Looking at the data stream, the signal is flat with just a little noise.

About a decade ago, the main culprit of wheel speed sensor problems was the sensor and wiring. Any damage to the wiring on a two-wire WSS mean a loss of signal. May OEs like GM and Ford made the harnesses more robust and even put three-wire WSS on some applications.

The latest culprit of wheel speed sensor failure has been loss of the reluctor or tone ring. This is happening on all vehicles where the tone ring is pressed onto the CV or tripod housing. Corrosion between the two components cause the tone ring to crack or even fall off. Replacement rings are available, but the coverage is not great. The only option in some cases is to replace the joint or the entire axle.