Last night, my IS250 AWD suddenly went crazy and lit the Brake, ABS and Exclamation indicator lights. And on the lcd, it said Check VSC and Check 4WD. On my way to the dealer this morning, the lights went off and the messages disappeared. When I got to the dealer, they connected the car to their computer and saw an ABS error. Something to do with debris blocking the ABS sensor. They reset it and test drove....and the warning lights and messages appeared again. Needless to say, I had to leave it at the dealer. They called me this afternoon to tell me that they have escalated to California HQ to see how it can be corrected. Apparently, the errors persist.

Anyone had the same experience?

 

DId the ABS kick in?

Typically, if the ABS sensor of one of the wheels is blocked, the vehicle will think that wheel is locking because it spins slower than the other 3 wheels. The ABS will kick in prematurely when you step on the brake, trying to overcome that locking wheel (that's what AntiLock in ABS is for right?), which in reality is not necessary at the moment.

Happened on my Audi A4 before: ABS kicked in everytime I step on the brake pedal.
There was oil "grimme" that blocked (contaminated) the ABS sensor.
Turns out that the CV boot is torn and the lubricant inside the cvjoint assembly spayed all over the front right wheel and covered the ABS sensor with gunk.

Good luck.
Keep us posted!

 

Toyco uses magnetic sensors. They are unaffected by grease or dirt. Because the warning lights came on, the ABS was disabled. That's the failsafe behaviour indicated in the FSM when a wheel speed sensor stops working. It will not enable ABS until the system passes the self-check on start up.

I doubt it was debris. More than likely a road hazard damaged the wire to the sensor. It's unlikely, but possible. An intermittent wire connection to the wheel speed sensor would create symptoms just like you described.

 

Just got the car back after two days at the dealer. The rear right brake sensor had some sort of debris stuck to it causing the ABS and VSC to get disabled.

 

So it took them 2 days with a call to the higher ups to narrow it down to "debris stuck on the sensor". Something makes me think that they aren"t telling you the whole story. I don"t know if you are aware of it or not but on most late model Lexus(if not all of them) when the engine management computer senses a fault the abs/trac and awd systems are automatically shut off, the reasoning behind this is that if the car is not running properly then these systems can't function properly. It still amazes me to this day the number of mechanics who try to chase down a code set in the abs/trac computer when the fault really lies in the engine computer

 

The only kind of debris that would affect your wheel speed sensor is a piece of ferrous metal. It would have to get stuck to the end of the sensor. It should be painfully obvious to a tech if that is the case. The fix sounds fishy.

Did you see the repair order? Did they replace any parts?

 

And being that the space between the sensor and the tone ring is only about 1/16" I doubt anything lodged in there.