I have a 2000 rx300 awd w/o traction control. On dry pavement the ABS activates but there are no lights going on on the dash, no failure codes collected in the ECU and upon testing the sensosrs while on a dyno, they appear to be putting out normal sine waves. Any ideas as to where to go next. My repair tech is reluctant to replace the computer but it seems as though we are getting to that point. The tone rings 'appear' ok. The rear sensors were tested in place due to the risk of destroying them with removal. Based on posts that I have reviewed, it seems as though it is unlikely to be sensors. We have verified that the tires are inflated correctly. On loose soil, the ABS does function properly. It seems to go off randomly when it should not do that maybe every hour or so when driving.

Thanks for your ideas.

 

Can you clean them without removing them? I would still suspect dirty sensors. Don't know if there is any room between the teeth on the ring to try to clean them or not. Is it intermitent or easy to replicate?

 

I had the same problem on my 2000 awd. Could not find the fault for months. All the sensors tested okay. Turned out to be a small crack in the tone ring which the sensor intermittently picked up. Somehow my tech tapped the computer, while moving, to produce sine waves to show which tone ring was at fault. It was a rear. Destroyed the sensor trying to remove it due to rust. The tone ring is part of the half shaft and expensive. I think the part was $875 CDN. I hope this helps.

 

You need to do some searching both here and at LOC. Many have had this problem in the past. I believe every one of them required a new sensor ring which is part of the axle shaft to fix the problem.

 

The problem happens sometime during each time that I drive it, but it is intermittent and sometimes difficult to replicate on demand.

 

The other issue besides clinging or axle rings is that the axle itself could be the issues.

I can tell yout that my ABS light has been on since Mexico, in 99.9% part due to my disconnecting the system, but also because shortly after cleaning the sensors, ironically, I could not get the ABS light off despite my uncle and I and even looking at with a Toyota shop scanner in Mexico what the issue was. As such, I am just waiting my time until the ABS bulb burns out.