FIXED: Brakes 'grab' -- seems different from previous postings

We picked this car up 5/19/06 in Moses Lake, WA. Fine for 1000+ miles. In the 800 miles since, the brakes very occasionally (30-40 times) have done the following:

When first pressing the pedal, nothing happens at all -- no slowing, no sound. Pressing harder eventually yields a sudden jerking stop, accompanied by an audible thump. This is VERY obvious, to passengers as well as the driver, and completely unlike every other time the brakes are used.

This happens most often at very low speeds, in very gentle braking -- the first times it happened to me, I was in stop and go traffic -- speeds from 0-5 mph. When using zero throttle (or even riding the brakes to keep the speed very low), and traffic stopped, several times in 20-30 minutes, the above happened.

Other times it will happen in a parking lot, or when gradually slowing for a light, stop sign, etc. Only a handful of times at more signficant braking (freeway exit or other stop from 30+ mph).

This happens to all 3 of us who drive the car, and we're all very 'gentle' drivers. (Actually, when driving at all aggressively, this doesn't happen.) It's major enough that my wife and daughter are now afraid to drive the car. (We also have a Camry Hybrid, which doesn't do anything like this.)

Unfortunately, it can't be reproduced at will, and we haven't been able to demonstrate it to the dealer folks, so they clearly don't believe us... Any similar experiences or suggestions?

Thanks --- Tom

 

UPDATE: Just back from dealer. They've had the car for 2 days and couldn't reproduce the problem, despite driving it 75 miles altogether. We went out for another drive with the tech and fortunately got it to happen once (took 20+ minutes...). They believe it now and will let us keep our loaner for our two week vacation (driving) while they try to figure it out and fix it. Although it was frustrating that they didn't believe us, I can't complain about the support we're getting.

I'll post when I hear from them...

 

Problem fixed, but not easily...

Fortunately, they took us seriously when the problem happened once with a tech in the car. We had the loaner for 3 weeks and 1500+ miles...

Toyota US had no record of a similar problem -- multiple consultations & suggestions, many new components (ABS 'brain', etc.), visit to dealer from Toyota 'super-tech'...no joy. Again fortunately, the service writer learned how to reproduce the problem fairly quickly, so they were able to verify 'not fixed'. Finally, in consultation with Toyota US, they put another car side by side with ours and started swapping brake system components. The part that fixed it was the 'brake pedal position sensor', says the service writer. Ironic, since when I first took it in, one of the things I said was that I had the feeling that the car wasn't properly sensing what I was telling it to do... Also, seems like an early candidate for replacement in the process.

Anyway, all's well that ends well. I got lots of free miles from the loaner, and the dealer's service department got $2200+ in labor reimbursement... The failed part has been sent to Toyota -- wonder if we'll see a recall?

-- Tom