Great site. I would have never been able to figure this problem out without first visiting and searching and reviewing all of the info for an ABS issue.
The story goes like this. '97 Camry. This is my sister's car so I have little repair history. She told me her ABS light was on constantly. She freaked when her mechanic told her $200 for the sensor + labor. I told her to let me look at it first.
I started by shorting the connector contacts and it read code 31. Right front. I proceeded to jack up the car (installed jack stands), remove the wheel, and remove most of the inner wheel well to get at the connector. I guess Toyota put it up there to protect it from the elements. After disconnecting the connector I did a resistance check of the sensor coil. 1545 ohm. That was in spec. So I proceeded to remove the sensor, remembering reading on the site that sometimes the sensors get dirty. I removed the sensor without issue (Texas is wonderful) and it was a little dirty but not bad. I proceeded to wipe it off. I then rolled the rag up a little to clean out the hole in the hub. When I did this I thought my eyes were deceiving me but I could have sworn I saw the ABS ring on the axle move. I inserted a small flat blade screw driver and sure enough the ABS ring was floating on the axle.
Inspection of axle indicated it had been replaced recently. I removed the axle and sure enough the ABS ring was not seated correctly. The retaining ring was also missing. This is why I do all my own work.
After looking it over I realized the ABS ring would require a little tapping to install in the correct position on the axle. I cleaned up the axle and ABS ring, sprayed with some brake cleaner and mixed up a little JB weld. I installed a light coating of JP weld on the axle and installed the ABS ring lightly tapping it with a hammer until it was seated in the correct position. I let it setup for 6 hours and began to put everything back together.
Drove the car about 10 hours later and ABS light went out after getting up to about 15 MPH.
Since this was something I had not seen I thought it might help someone else down the line.