I currently have my 1999 4runner at a shop that swapped my axle housing and rebuilt the rear. They were unable to salvage old ABS sensors and ordered new aftermarket sensors. After installing the sensors they cannot get the ABS light to go off.
Anyone have any suggestions as to why the abs would stop working after swapping sensors?

Some possibilities:

- ABS sensors are not the correct type (too far from the tone ring)
- ABS rings were installed on the axle shaft in the wrong position (along with the axle seal - there's an annoying air gap between them and the bearing when pressing things on)
- ABS rings installed don't have the correct spline counts
- ABS sensors have a wrong resistance and it is triggering fault detection on the ABS ECU

what he said. if a shop your paying money too cant figure it out...wrong shop or someone claiming to be a shop...is not

Thank you for the suggestions!

I am starting to figure out now that it was not the best shop. They are considered one of the best 4x4 shops in the area so I am very surprised I am having this issue.

If you unbolt the ABS sensor, you should be able to look down into the hole and see the ABS tone ring. If it's off to one side or another, that's a problem. The sensor needs to sit right over the ring.

If it's more or less centered in the hole, then try to carefully measure how far down it is from the mounting face of the sensor on the axle to the top of the teeth - where the sensor would sit. Then carefully measure how far the tip of the sensor extends down from the mounting surface as well. The sensor needs to be pretty close to the tone ring to work - somewhere between .5 and 1mm.

With a good multimeter, try checking the resistance. I'm not sure what the 'correct' reading for a rear ABS sensor is, but just check that it's not an open circuit, or a short circuit. if your multimeter has an A/C current voltmeter setting, you could try spinning the wheel and seeing if you get a reading. It passively generates alternating current as the splines pass the sensor tip. It's not a great test that everything is 'correct', but just a good enough test to see if it's dead or not.

And then just look at the wiring on the sensor, and on the car where it plugs in.