Does anyone knows what a rear axle speed ring is?

AUM

My highlander traction control system is engaging for no reason, someone sugested to check the speed rings in the rear axle drive. Can anyone sugest anything, the internet has been no help so far.

wondering

The speed rings (which are usually called tone rings) have a bunch of square top teeth on them and are read by a magnetic sensor that sends 1 pulse of electricity to the skid ECU each time a tooth passes. If the pulses aren't getting to the ECU or are scrambled and noisy due to a rusted ring it thinks either the wheel (ring on hub) or axle (ring on driveshaft/pinion gear shaft) is locked up and not turning or is turning the wrong speed and starts doing everything it can to try to get it rolling correctly again which means engaging the traction control and/or the anti-lock brakes. An excellent picture of one is here in the first image: http://4x4icon.com/offroad/rear_axle_bearing/