New Prius Brakes Releasing If You Hit Pot Holes!

[DaronB]

Just wondering if anyone else has experienced this in the new Prius, ours is 6 months old now and has done this from new, Toyota say they're not aware of any issues. Basically if you are slowing down with the brake pedal pressed coming up to a junction or traffic lights if you hit a pot hole with one of the wheels the brakes compltetely release for a couple of seconds, enough to send you freely rolling forward about 4-6 feet before they re-apply, this could be really dangerous if you were close behind another car you would likely run into it.

Because we're aware of it now we leave extra room when braking in case it happens but I still feel its very dangerous and should be resolved. Anyone else had this problem?

[vishalpal]

Not sure if yours is the same problem but check this out. Looks like Toyota might soon have to do a recall on the Prius too due to a problem with its brakes. Toyota till date have managed to dodge this issue but how long can they be ignorant until someone files a lawsuit which might have caused a serious accident.

http://news.bbc.co.uk/1/hi/business/8495132.stm

[DaronB]

Not sure if yours is the same problem but check this out. Looks like Toyota might soon have to do a recall on the Prius too due to a problem with its brakes. Toyota till date have managed to dodge this issue but how long can they be ignorant until someone files a lawsuit which might have caused a serious accident.

http://news.bbc.co.uk/1/hi/business/8495132.stm

I think you've hit the nail on the head there, this will be the next recall. Our supplying dealer said there was nothing on their system about any problem with brakes but the first time this happened shortly after we got the car it scared the c**p out me. When you hit the pothole the brakes totally release then reapply about 3 secs later but its that few seconds when your sailing forward freely that really scares you.

As I said because we're aware of it now we leave extra space from the car in front as if this happened and you were 10 feet away I've no doubt you'd rear end the car in front.

Thanks for the info i'll pass it to our dealer.

[flow]

Ive experienced this problem quite alot - normally, as mentioned, when you brake while driving over a pot hole or bump in the road.

There are many posts over on priuschat about it. Some people say that, even though you feel the car has lost traction and shoots forward - its just the change in braking that gives that impression.

Spoke to Toyota last year about it - nothing they could do.

[DaronB]

Ive experienced this problem quite alot - normally, as mentioned, when you brake while driving over a pot hole or bump in the road.

There are many posts over on priuschat about it. Some people say that, even though you feel the car has lost traction and shoots forward - its just the change in braking what gives that impression.

Spoke to Toyota last year about it - nothing they could do.

I disagree, you can feel the brakes physically release then reapply, the car does pick up speed as the brakes release. No question.

[johalareewi]

I disagree, you can feel the brakes physically release then reapply, the car does pick up speed as the brakes release. No question.

Techincally, that can't happen. If the brakes release, the car just stops slowing down.

It needs the accelerator to be pressed to speed up (or be on a steep downward slope).

But it will certainly feel like the car is speeding up.

This is how those fairground driving simulators work.

You think you are accelerating and braking sharply but in reality, you are hardly moving.

Being discussed here...

http://toyotaownersclub.com/forums/index.p...howtopic=106635

And it has been on prius chat for some time.

See this latest thread for serious investigation by Prius owners.

If you can reproduce the problem, contribute to the thread with google map location and details.

No <me too> posts though.

http://priuschat.com/forums/gen-iii-2010-p...ake-system.html

[DaronB]

I disagree, you can feel the brakes physically release then reapply, the car does pick up speed as the brakes release. No question.

Techincally, that can't happen. If the brakes release, the car just stops slowing down.

It needs the accelerator to be pressed to speed up (or be on a steep downward slope).

But it will certainly feel like the car is speeding up.

This is how those fairground driving simulators work.

You think you are accelerating and braking sharply but in reality, you are hardly moving.

Being discussed here...

http://toyotaownersclub.com/forums/index.p...howtopic=106635

And it has been on prius chat for some time.

See this latest thread for serious investigation by Prius owners.

If you can reproduce the problem, contribute to the thread with google map location and details.

No <me too> posts though.

http://priuschat.com/forums/gen-iii-2010-p...ake-system.html

Surely if it stops slowing down then it is speeding up? Just noticed its now a headline over on the Sky News website

http://news.sky.com/skynews/Home/Business/...he_Last_Quarter

[wooski]

Surely if it stops slowing down then it is speeding up? Just noticed its now a headline over on the Sky News website

http://news.sky.com/skynews/Home/Business/...he_Last_Quarter

No - the sensation of changing from slowing down to not slowing down is an acceleration but the car does not get faster - it just stops decelerating. Just because there is an acceleration does not mean the car gets faster! It's like when you brake suddenly and youre thrown back into your seats when you fully stop. The force that does that is an acceleration as you change from deceleration to stop. But the car doesnt move.

[Grumpy Cabbie]

You don't speed up or accelerate but you stop slowing down! That makes it difficult to stop as you might judge to stop within a certain distance but this distance is increased because of the 'fault' and that could cause an accident.

Things get worse. Apparantly Toyota have been aware of this and have put a correction in place for new cars as of January this year but nothing has been done about the existing vehicles already on the road. Hmmmm.

My dealer is aware of my concerns and they are taking it seriously. I will keep you informed and updated.

[Grumpy Cabbie]

Just seen this article today. Toyota have admitted the problem as a software problem.

http://news.bbc.co.uk/1/hi/business/8497471.stm

Hope all will now be sorted under a recall.

[wooski]

Just seen this article today. Toyota have admitted the problem as a software problem.

http://news.bbc.co.uk/1/hi/business/8497471.stm

Hope all will now be sorted under a recall.

On CNN Too

[wooski]

Toyota UK still sticking with the line all is ok and no recall - Toyota UK Statement on Prius

[Grumpy Cabbie]

Just seen this article today. Toyota have admitted the problem as a software problem.

http://news.bbc.co.uk/1/hi/business/8497471.stm

Hope all will now be sorted under a recall.

On CNN Too

Just rung Toyota and got a useless call centre in Africa reading from an out of date script. They said there is no problem in the UK and when I told him the news says different he hung up! Nice!!!!

I have also had the BBC contact me (probably cos I'm a taxi?) wanting to know full details. I'd really rather not, but if Toyota don't do something here I might. I know it takes time for a big organisation to move and this issue is fast moving but please don't insult my intelligence with some useless call centre reading from a script.

Aggghhh

There, I feel better now

[johalareewi]

No - the sensation of changing from slowing down to not slowing down is an acceleration but the car does not get faster - it just stops decelerating.

I think you meant a change in acceleration (or j.e.r.k) <-- forum filter doesn't like the word!!.

When the brakes are on, there is negative acceleration so you are slowing down.

If the brakes fail, the acceleration is now zero and you stop slowing down.

This creates positive j.e.r.k (change of acceleration).

The positive j.e.r.k gives the feeling of acceleration (it is the same feeling as when actually accelerating)

Which is why people say the brakes failed and the car accelerated.

Anyway, nice to see toyota are looking into it even though I haven't experienced the problem.

Even if it is safe, it shouldn't scare the c**p out of people.

[johalareewi]

Toyota UK still sticking with the line all is ok and no recall - Toyota UK Statement on Prius

Funny how they can say no reported cases in the UK when people in the UK have been reporting it.

Wonder what the toyota definition of a reported incident is?

[Grumpy Cabbie]

Toyota UK still sticking with the line all is ok and no recall - Toyota UK Statement on Prius

Really?

In that case I suggest you ring Ana Lucía González at the BBC on 020 8576 8200 and maybe Toyota might sort this issue out now!!!!

[posing]

I experienced the seeming speed up after a pothole problem too, many time since I had the car. The skidding car symbol flashes up when this happens. I'm thinking of average 3 times a year. Each time it happens, I do get a fright. It happened this morning and also happened during the heavy snow as I was braking to a stop at a roundabout on a M1 junction. That time it was truly scary as I was going slow anyway due to the snow and then I lost brake power for a split second as I was coming to a stop with cars going around the roundabout. I ended up with my front a little edged out onto the roundabout rather than be behind the line if braking worked normally. Thankfully the others were going slow too and avoided a collision.

I will be keeping a close eye on the recalls.

[flow]

Toyota must clearly know there is a problem...Its now been reported on here & Priuschat, not to mention all the people that contacted their local dealer about it.

Im assuming, because the car doesnt physically accelerate (just gives that sensation) they are saying its not dangerous?

[Grumpy Cabbie]

Toyota must clearly know there is a problem...Its now been reported on here & Priuschat, not to mention all the people that contacted their local dealer about it.

Im assuming, because the car doesnt physically accelerate (just gives that sensation) they are saying its not dangerous?

Have spoken to Toyota this afternoon and they are aware of the problem and will probably (no decision made yet) be issuing some sort of special update rather than a recall. Apparantly a software upgrade can solve the issue and smooth out the problem. I take my car in for service in a couple weeks and will stress the issue then. I'm not going to let the issue go away and I don't believe Toyota will either. We shall see but I do feel happier and more confident having spoken to Toyota.

[DrCez]

Toyota must clearly know there is a problem...Its now been reported on here & Priuschat, not to mention all the people that contacted their local dealer about it.

Im assuming, because the car doesnt physically accelerate (just gives that sensation) they are saying its not dangerous?

Quoting this article on the BBC website:

"As depressing the brakes further activated normal braking, Toyota said the glitch was not legally a safety hazard and said it had received no reports of any accidents related to it."

This is exactly my experience on the two occasions I have experienced an unexpected reduction in braking with my Gen 3: the first time it was scary but I instinctively pressed the pedal harder and the car began slowing again. The second time (a few months later) I ran over a damaged drain cover while braking but I suppose I was more prepared to push the brake pedal harder and it wasn't particularly frightening. Some are suggesting that the problem is more apparent in certain cars; in my case it's infrequent enough not to worry me but were anyone else to want to drive my car I would warn them to watch out for this unusual behaviour.

I suppose part of the problem is that other cars don't behave like this: for a given amount of brake pedal depression you get more-or-less even braking force, and in this respect the Prius could catch you out. If it can be remedied with a software fix then all the better.

Thanks to all for keeping track of the issue, it's really valuable information, so keep on posting :)

[The Traveller]

Toyota must clearly know there is a problem...Its now been reported on here & Priuschat, not to mention all the people that contacted their local dealer about it.

Im assuming, because the car doesnt physically accelerate (just gives that sensation) they are saying its not dangerous?

Quoting this article on the BBC website:

"As depressing the brakes further activated normal braking, Toyota said the glitch was not legally a safety hazard and said it had received no reports of any accidents related to it."

This is exactly my experience on the two occasions I have experienced an unexpected reduction in braking with my Gen 3: the first time it was scary but I instinctively pressed the pedal harder and the car began slowing again. The second time (a few months later) I ran over a damaged drain cover while braking but I suppose I was more prepared to push the brake pedal harder and it wasn't particularly frightening. Some are suggesting that the problem is more apparent in certain cars; in my case it's infrequent enough not to worry me but were anyone else to want to drive my car I would warn them to watch out for this unusual behaviour.

I suppose part of the problem is that other cars don't behave like this: for a given amount of brake pedal depression you get more-or-less even braking force, and in this respect the Prius could catch you out. If it can be remedied with a software fix then all the better.

Thanks to all for keeping track of the issue, it's really valuable information, so keep on posting :)

A brief report on the BBC News channel late this afternoon suggested that Toyota have admitted a software problem between regen braking and ABS. They are now working on a fix.

[dmeredith]

My wife and I both have the problem regularly on our 4 month old Prius when going over speed humps - the brakes release for about 1 second as the front wheels leave the hump and go back onto the road. The main problem we have is that there is a speed hump near us that is just before a turning on the right, so if someone is turning right (and they often don't bother to indicate until they start to brake for it) you have to brake as you go over the hump and the momentary loss of braking causes you to get much closer to the car than you'd like!

It seems to be related to regenerative braking as it doesn't seem to happen when braking over humps if you put the car into neutral first (in drive I can repeat it nearly every time). Having monitored road speed while repeating the effect it's clear that the car doesn't accelerate, but for about 1 second (just under) the car stops decelerating and maintains its speed.

Hadn't mentioned it to Toyota as we were waiting for the 10K service to come up, as no-one else seemed to have had a fix for it anyway.

[Scottle]

I've had this happen four times in the month that I have owned my Gen 3.

As for the feeling of acceleration when this happens could this be due to the car having an auto (CVT) gearbox and as such when not braking the car will accelerate, just as when you release all the parking brake with the car in drive??

[Fujisan]

I am sorry, I my opinion, this is no more than just a characteristic of the car.

If you owned a powerful rear wheel drive car, even before you sat in it you could expect that if you entered a bend too fast, the back end to come out and depending on your skill level, you might head backwards into a hedge. That is the charactistic of that car and with correct reading of the road you would avoid the situation.

This is slightly different in that this characteristic is only revelled either by research on forums like this or PriusChat or by first hand experience.

Having experienced this characteristic myself once and I'll agree that it isn't a nice feeling, but we then should be able to recognise the road conditions that might provoke this characteristic and alter our driving accordingly where possible (brake earlier on a smooth surface, give extra distance between cars, etc) and in unavoidable situations expect and not be shocked by this characteristic.

Some people have mentioned that they felt this characteristic over several seconds. I wasn't in the car with them so I will not disagree with their assessment. But in my opinion, milli-seconds would be a more accurate figure, even if it felt longer.

I will ask you to do a few small experiments:

Just count to yourself while you press the brake pedal in any given situation and you will be amazed just how short a time you are actually on the brakes and how quickly speed is scrubbed off.

Next, travelling at a steady speed, when you pass a landmark (road sign, whatever), count to yourself, two or three seconds and then look back in our mirror and see just how far you have travelled in those two or three seconds.

If Toyota do have a software fix for this characteristic all well and good but in the mean time I will rely on reading the road correctly, using correct observation (I am sure any former bikers know the importance of watching out for diesel spill's on the road surface) to be cautious when braking on broken road surfaces.

[Grumpy Cabbie]

I am sorry, I my opinion, this is no more than just a characteristic of the car.

If you owned a powerful rear wheel drive car, even before you sat in it you could expect that if you entered a bend too fast, the back end to come out and depending on your skill level, you might head backwards into a hedge. That is the charactistic of that car and with correct reading of the road you would avoid the situation.

This is slightly different in that this characteristic is only revelled either by research on forums like this or PriusChat or by first hand experience.

Having experienced this characteristic myself once and I'll agree that it isn't a nice feeling, but we then should be able to recognise the road conditions that might provoke this characteristic and alter our driving accordingly where possible (brake earlier on a smooth surface, give extra distance between cars, etc) and in unavoidable situations expect and not be shocked by this characteristic.

Some people have mentioned that they felt this characteristic over several seconds. I wasn't in the car with them so I will not disagree with their assessment. But in my opinion, milli-seconds would be a more accurate figure, even if it felt longer.

I will ask you to do a few small experiments:

Just count to yourself while you press the brake pedal in any given situation and you will be amazed just how short a time you are actually on the brakes and how quickly speed is scrubbed off.

Next, travelling at a steady speed, when you pass a landmark (road sign, whatever), count to yourself, two or three seconds and then look back in our mirror and see just how far you have travelled in those two or three seconds.

If Toyota do have a software fix for this characteristic all well and good but in the mean time I will rely on reading the road correctly, using correct observation (I am sure any former bikers know the importance of watching out for diesel spill's on the road surface) to be cautious when braking on broken road surfaces.

It has happened to me a number of times and can be milliseconds or on one occasion about a second or so! It depends on the road surface I believe as well as your reaction time!