Wheel sensor how to diagnose if tone rings are bad. can they be replaced or must you replace half shaft

What make , model an year vehicle ? Is the wheel speed sensor integral to wheel bearing hub or separate ? Could be a corroded tone ring on half shaft . ABS activates on every stop damaged tone ring

Rather than just the bearing, I suggest a new half shaft as the bearings and ABS tone wheel are already assembled. These Escapes are notorious for cracking the tone wheel setting off a code and then disabling the AWD system. So for a very few dollars more than it would take to disassemble the shaft , install bearings and tone wheel just get a new one.

Turn the axle and look at every tooth if you see it cracked any where in between then shaft will be needed as these are pressed on.

The sensor operates in conjunction with the TONE RING, located on the axel under the sensor. The tone ring is probably physically broken due to rust swelling. The tone ring resembles a gear and the sensor "sees" the notches on the ring. When the ring breaks, the sensor can't read it correctly. Part is 6 bucks from rock auto. Installation is quite involved(remove axel). There are instructions posted somewhere online. Search! Get ready because I think all 4 wheels have this ring and they WILL all break at some point. Oh when the right front ring goes bad, you will think the motor is falling out. Clunk, bang. losses power but new ring will fix.

Most common problems that cause an ABS light in the XJ is a bad clockspring - located in your steering wheel, or the ABS tone rings themselves rusting too much. The tone rings are the toothed rings at the end of each of your axle shafts.

The clockspring would have to be replaced, but the tone rings can often just be cleaned of rust so that the ABS sensors can read them again.

Since you replaced the pick up units or sensors, check the tone rings on the axle shafts. The tone rings is what the sensors detect and are located at each wheel that has ABS. A tone ring looks like this:


This tone ring is on a Ford Ranger - which is pretty much the same as your Mointaineer. Notice the break in the tone ring. This will cause an ABS Fault indicator and will need to be replaced to extinguish the lamp. Check the brake fluid level and top off if needed.


Try another AutoZone or similiar to get a code and be non-specific about the light - just say a light came on on the dash and you don't know what it is about.

Good luck!

2008 Escape has a terrible reputation for ABS light and traction control light being. All due to broken ABS tone ring cracked and out of position flopping on frt bearing. Go to local AutoZone store and they will scan this to find which wheel has the broken tone ring. The replacement ring is cheap in the $7 range. It is labor that will sicken you as this ring must be pressed on after the front half shaft is removed. Not a driveway job if you are considering DYI.

Sounds like you may have a broken abs tone ring on the front axle shafts they have a problem with that start there

here is how I do it.
http://youtu.be/3xZBld7MW8E

The speed sensors are a single pole, variable reluctance sensor, mounted to the rear axle housing and both front half shafts.

A toothed tone ring is press fit to the differential carrier next to the drive gear and provides the signal for the rear sensor.

The front tone rings are press fit to the half shaft assemblies