I have a 2003 RX300 that falsely activates the ABS motor very lightly when coming to a stop. It doesn't start till your down to about 5 to 10 mph and doesn't do it every time. It makes a chattering kind of sound.
I pulled some waveforms off each sensor as I turned each wheel, and found the left rear to be much different than the other 3. I was back probing the connector at the controller. At first the left rear was almost hard to find the waveform in all the noise. Although, as I rechecked some of the others again and came back to it there seemed to be less noise. The noise also seemed somewhat intermittent too as you can see in the pics. I did not turn on the ignition when performing the tests. When I unplugged the connector from the controller and observed the waveforms, all 4 seemed to have additional noise. I'm thinking that when connected to the controller there is extra circuity that may help reduce the noise. The left rear is the only one the noise wasn't reduce when connecting back to the controller. All the resistances were similar between 1000-1400 ohms, although at first the left rear did seem to have 800 ohms, but didn't see it again.
I looked for a glitch pulse on each of the waveforms which would indicate a cracked or broken tone ring, but did not notice any. The waveforms were all smooth for at least a complete rotation.
The only thing I could conclude was because all the sensors looked the same when unplugged from the controller, and only the left rear did not change when plugged in that it was the controller.
I replaced the controller and the problem still exist.
Now I'm left with either a bad sensor, or broken tone ring. I have to believe I could detect a bad tone ring by the waveforms, so I suspect it's the sensor.
I'm wondering if anyone has observed similar waveforms with a lot of noise and can give me some feedback. I hate to change the sensor and find it still didn't fix it.
Any feedback would be appreciated.
I attached pics of the Right Front, Left Rear, and a comparison of the Right Front with the Left Rear. The Right Front I'm assuming is good.