2010 Prius Brake problem not resolved even after dealer correction

Excellent! These are the types of technical details needed to understand and hopefully replicate a problem.

This shows the intersection of Simcoe St, Regional Road 15, and Thorah Side Rd. I see the creek that meanders through the area. Was the dirt road accessed via Rr. 15? If so we might get a reasonable view from Street view before the detour.

Regardless, I asked the local Usenet group for "the worst roads in North Alabama" and have some candidates to check out:

• Zierdt Road - east of Marshall Space Flight Center
• 'bumps on the slow down lane at Slaughter Road'
• Keel Mountian
• Explorer Road at SAIC
• Drake Avenue east of Whitesburg Drive
• [ame=http://maps.google.com/maps?f=d&source=s_d&saddr=34.836068,-85.979004&daddr=Co+Rd+39&geocode=%3BFYSLEwIdiUbg-g&hl=en&mra=dme&mrcr=0&mrsp=0&sz=13&sll=34.832968,-85.980892&sspn=0.082428,0.132351&ie=UTF8&ll=34.834906,-85.973382&spn=0.020607,0.033088&t=p&z=15]Co Rd 39 to Co Rd 39 - Google Maps[/ame]
• Sparkman Drive past the first traffic light north of UAH when the road turns right until the next light. Left lane is especially bad for 100 or 200 yards of continuous poorly patched potholes.

I've got some candidates to check out and I'll try to post some metrics.

Thanks again!
Bob Wilson

 

I had the ECU updated last week. Prior to the update, braking over a bump or pothole would result in a little 'skip' on the road as the brakes kind of fluttered. I just pressed the pedal a little harder and all was well.

Post update, I have a serious problem. I have also experienced the brakes letting go completely as the car hits a bump. The little 'skip' is gone, and now there's a panic moment where the car lurches forward with no brake pressure. I have to really mash the pedal the get the brakes back.

Reading this forum, it seems this is not a common result from the update, and I guess I will have to take it back to the dealer to see if they can revert the ECU version. If not, then I will have a big problem, because it's really not safe. Of all the beaters I ever drove, even the worst rustbucket never had a problem like this, which makes me really disappointed for having bought a Toyota.

 

I had my brake fix done about two months ago when I brought it in for an oil change. After 2 months, I would say the brake lapse happens about half as often and is about half as severe when it does happen. There was one spot when turning into my driveway where it used to happen to me often, now I can't even cause it to happen.

 

Having had the software update back in feb I thought everything would be ok.

However on saturday as I was turning around in a car park the brakes failed to engage at all and my foot was fully to the floor.

The result was me nosing into a breeze block wall and scuffing up the front leading edges.

I was not going at a great speed as I was in a car park and if anything didn't have the space to get up to speed!

It felt as if the car was in neutral and made no attempt to stop.

There was no signs of the breaks engaging as any loose stones had not scraped on the floor and no tire marks (not to be expected at such a low speed anyway).

I immediatley phoned my local dealership which was only 1/4 mile away (approx) and informed them of the issue.

As they had no way of collecting the car I tested the brakes a few times and set off (very carefully) and below the speed limit to the dealers.

I got a call on the Monday from the head engineer saying he cannot find a fault after all the tests.

He then mentioned that there may have been a conflict between the engine assisted braking and the regenerative braking causing a lapse in the ability to break.

He did point out it could be a one off event but did not deny the possibility of it happening again!

I am now in the process of trying to get Toyota to do the repair work as it is a fault in their car which is still under warranty... but as their tests do not show a problem they say they are not liable!

So I just wait until they fail at 70 mph and someone gets seriously injured for them to take notice..

If only I hadn't got the car on finance cause I very much want rid of it.

With a pregnant fiance and a 3 year old son I'm not in the business of taking risks!

 

In the US, do you have road side assistant.?
You should had the General manger come and look at the car and area better you moved the car after hitting the wall, and have test the black box
If they would not come, tell them you phone a TV station

With moving the car, it is down to he said, she said

 

They had no way to come collect it and I said I was not confident in moving it any distance.

In hindsight I probably should have not moved it but with my hands still shaking from the shock I guess I was more worried about my unborn child and fiancé than the legal ramifications...

Having spoken to a rep from the motor industries onboardsman he has suggested I get an independant report from atleast 2 other sources and then go back to Toyota with thier findings!

The cars' 'black box' reported no fault... but as with any software if it has not been programmed with the parameters of the incident it will not find a fault.. I'm guessing this incident falls into this grey area and is therefore being overlooked...

 

It is difficult to diagnose an intermittent problem, one that happens randomly and can not be reproduced at will. The "black box" can capture some incidents but it usually it requires something to trigger the record being kept (aka., air bags.)

There are vehicle recording systems, often with cameras, that are used to document accidents by fleet owners. They has a small disk drive, camera and can include sensors for the car. A couple of hundred dollars (US,) it would provide an independent verification of a problem.

We have had a number of reports of people pushing the wrong pedal. You might check the pedal placement versus other cars to see if the Toyota Prius placement seems different or 'off.' Just a thought.

Bob Wilson

 

Passanger observed at time of incident that foot was fully depressed on the brake pedal...

Also if I had hit the accelerator we'd have gone through the wall and not just rolled into it!

 

Did anything else happen at the time, like a chime going off or indicator lights illuminating?
Did you hit a bump as you where braking into the parking spot?

 

No warning lights or noises..

Flat concrete surface with a small amount of loose pebbles (2-3 mm big), not covering the surface just in places where they have worn off the main surface over the years..

Clear dry day and no mud or any other materials that could come loose..

It was as if the car went into neutral whilst attempting to brake and it coasted into the wall.. no skidding, vibrating or slowing of any kind.. just rolled forward with no time to apply the foot brake

 

My understanding is that if the electronic brake assist fails, unassisted hydraulic braking should still be in place and would presumably would stop the brake pedal from being fully depressed.

Its not clear to me how the problem you describe could occur. Has anyone got any ideas?

 

Unless it was not the switch over at the root of the problem.

I had a similar experience with mine this spring. I was approaching a heated sidewalk and about 15' before the walkway lines where the heat stopped and the ice began, there was a sharp ridge of ice (about 3-4" high and 2-3" wide). I struck that ridge at about 10-12mph, gently riding the brake. As soon as I hit the ridge with the front tires, an indicator light went on (no sure which), a couple of beeps, and the brake pedal sank all the way down to the floor. The car came to a stop within the walkway lines. Fortunately nobody in the walkway. In this case, I could not press the pedal down any further for more braking. Perhaps I could have pumped the pedal but I am sure that would have increased my stopping distance.

I got the brake update done soon afterwards.