New member trying figure out this issue. My son has a 99 RX300 AWD. The ABS system activates at slow speeds most of the time while braking. The ABS light only comes on when on the highway for a period of time and then goes off shortly after getting off the highway. The rear speed sensors have been replaced which was supposed to repair the issue. The local garage has told me that a Lexus dealer needs to look at it with their software. Any thoughts?
Thanks for your input!

 

very possible that he has a broken tone ring on one of the axles... the sensors sense the speed of the tone rings and trigger abs when it senses an anomaly. Other places to look is to check for any magnetic debris sticking to any of the abs sensors.

 

There are additional diagnostics through the brake port and also by reading flashing light in the cluster (please search). Before chasing the fault, have the alternator/charging_system/battery checked out. I spent months on mysterious ABS codes and they got fixed once I replaced the diode pack in the alternator.

Salim

 

Hi all - new frustrated member. I have a similar issue where the abs engages at very low speeds. It is the right front that is grabbing. The sensor is clean and has 1.6k - 1.7 ohms of resistance. The tone ring is in good condition with no chipped or missing teeth. I can also see small chunks of tire missing on the right front. What is my next step? I have read a lot of posts but none say "repair this...and all is well" I see many owners where they have started to replace sensors, axles, hubs and still have the problem. Also, no warning lights to indicate any issue. Thanks in advance

 

How do you know it's the right front?

 

Upon slowing down I can feel and hear the abs activate on the front right. I disconnected the right front sensor and took a test drive. I now have the ABS and VSC lights on the dash (previously no lights) and brakes were back to normal. I just used a Bosch scanner - one of the frequent repairs was to check the left rear sensor and tone ring. PB soaking on the bolt now

 

With the light on the ABS system is disabled. So that doesn't actually prove the problem is in the front right