Got into an accident today due to brake problem =(

btw, ur not going to get any love here b/c someone will turn the blame on you unfortunately. I think you walked into a bear trap.

The car does skip though forward if you are cruising fast enough and hit deep enough ruts.

 

Maybe this could help you ?
http://priuschat.com/forums/gen-iii-2010-prius-technical-discussion/78515-recall-brakes-did-not-fix-problem.html
But not sure - I think that the carrots are already cooked !

 

I know exactly what happened to the OP because it happened to me. It is user error.

I'm driving normally, I notice a intersection 100 yards away or so...I apply the brakes gently (regenerative) and the car slows down. However, the car does not come to a complete stop until I'm almost in the middle of the intersection. I pressed the brakes really hard to at the very last moment because I noticed the regenerative brakes won't stop the car in time. This happened to me several times and I often end up in the middle of the intersection. This is user error.

It looks like the rate of pressure applied on braking indicates which system will do more braking. I noticed if I apply brakes gently and increase gradually...it will use regenerative brakes and I will stop PAST the point I expected the car to stop. If I apply brakes and increase the pressure faster.....it will use the actual brakes and the car will stop in time.

There is definitely a threshold for the actual brakes to kick in unless you slam the brakes. If I hit a bump while using the regenerative brakes only....I have a loss of brakes for half a second or so. When this happens, it feels like the car is accelerating for a moment. It does not happen if I'm using the actual brakes.

So, the Prius requires a different driving style (which includes changing how you brake).

 

So you did not stop and entered a travel lane without having the space to do so. Sounds like you were driving too fast for the exit ramp and Merge into traffic. More caution, and experience could have saved you. The insurance company won't buy the excuse that the car did this, the car you were driving and should have been in control of, so I'd avoid the embarassment and tell the truth or say you were distracted for a moment, or the truck was in your blind spot, whatever.

 

If this issue arises from having regenerative braking in use when one hits rough road (and, I guess, the presence of VSC on the car), then it's possible that the same issue occurs in other hybrids.

Does anyone have a relatively easy way to find out if Insights, Fusions, Escape's, etc. have a similar problem?

 

You left your braking too late. Simple.

Those who think it's Toyota's problem simply don't understand the design of the car. Prius responds the way it does to ensure the HSD doesn't break (an abrupt change in torque as the wheel leaves the ground going over a sharp discontinuity in the road). That's kind of funny, to keep the HSD from breaking the car keeps from braking.

You and everyone else who experiences this did NOT speed up when it happened. It just feels that way when the braking (regen) releases for 1/2 sec or so until the friction braking takes over.

I say again, if 1/2 sec of release of regen braking causes you to hit something or stop way too long, you're LEAVING YOUR BRAKING TOO LATE!!! Stop racing about, drive carefully.

And learn to lean on the brake pedal in a car with ABS.

 

I don't understand why people read these posts (and there are obviously a lot of them), and then post responses. It is so predictable. Just let it go! It doesn't matter if they are trolls or uninformed or the salt of the earth. If anyone wanted to they could read several long threads about this subject and get their fill of it, as I have.

 

I have experienced that forward lurching during braking in my Prius as well. In fact it happens every day and at the exact same place on the road. This is not a dangerous thing and it is rather predictable. Moreover, the "lurching forward" is only maybe 1 foot forward at its WORST. That is completely controllable.

(There are certain conditions that make the car do this. It has something to do, of course, with the braking-return-force recharge transitioning to the normal braking pad system.)

This car is not made to be driven like a sports car. As a bus is not made to be driven like a helicopter. Nor is a submarine made to be driven like a tricycle.

I agree with ALS~
"I normally don't suspect a conspiracy but funny how these newbie posters always show up in waves. One posts a braking problem and we get a whole flock of newbies that show up with in a day or two with the exact same problem."

I read somewhere that if the price of gas goes up 0.001% at least 50 people become millionaires. The oil companies have MUCH to lose if we are NOT driving gas-guzzlers.

...oh wait, there's a red laser dot on my chest. uh oh, there's a knock on my door.

be right back...

 

Sorry to hear about your accident. There have been a number of threads dedicated to the Prius and its braking "issues". It seems that when going over rough/bumpy/potholed surfaces a situation can arise that causes an interaction between the Vehicle Stability Control System (to prevent rollovers) and the Antilock braking system that will increase stopping distances.

Your best defense is to reduce speeds if you expect to come across a patch of road like this. Otherwise, always try to stop 5 to 10 feet further away than you might otherwise want to stop, to give you an additional "cushion" in case something unexpected happens. You can always creep forward, under electric power, to your normal stopping distance.

 

i have a suspicion that the car does skip though forward if you are cruising fast enough and hit deep enough ruts because if it didnt tha car whould jam and flip over causing a biger accsident !

ps.i also got the lunge forward today when coming to a slow down over a manhole cover that wasnt resesed with the pavement but so did the peugeot not the same way but it also skiped big time! i think it has to do with asr srs wachukalamikate them terms!

i am going to be extra carefull from here on in ! because i wont be able to absorb being unemployed because of a brake malfunction.
i just bought the thing and it is suposed to have the programing done from the factory! hmmmmmmmmmmm lets see what goes!

 

Just for the heck of it, let's take this report at face value.

It seems that if the Prius was behaving as designed, then the cause of the problem has to be one of two things:

1. The driver made an error and waited too long to brake.
2. The Prius does not "respond" the way drivers of other cars expect.

I think the problem is most likely number 2. Those of us who have been driving a Prius for years have developed the instinct to appropriately apply the brakes and avoid this problem.

New drivers to the car are still assuming that what worked in the past on other brands will work with a Prius. This isn't a bad assumption to make. Part of the giant engineering effort in the design and improvement of the Prius has been to give the car the "feel" of a conventional motor vehicle. Nothing in the advertising or owner's manual suggests otherwise.

I have had my 2010 for almost a year now and I can't say that I have experienced this problem. That doesn't mean the problem isn't real. It just means that so far it hasn't hapened to me.

At worst we have an engineering failure and at best we have a slight adjustment needed to drive the Prius. I think we have yet another issue in transitioning from a conventional car to a hybrid.

The Prius has a very aggressive stability control and, after the software update, a more aggressive ABS. I can see how that combination could cause some trouble on an extremely bumpy surface. To the car it must feel a bit like an icy road where traction suddenly dissapears are reappears. The car's first reaction is to get the wheels moving at the same speed and to avoid any chance of loss of steering control. This should result in a reduction of brake force (think of what happens when you put on the brakes on an incy patch of road) on one or more wheels. This would be felt as though the car lurches forward, since we expect our speed to continue to fall.

I am not convinced this is a Prius-only issue. I suspect that other cars and trucks with very aggressive ABS and stability controls would perform the same way.

In short, let's consider this a learning experience and just like we do on icy roads, we should be very conservative with brakes on a very bumpy road.

 

No one should have to "understand the design of the car" to use the brakes just as they function in other cars. That's completely absurd. If that's the case, then everyone should be happy to admit that the Prius-haters are right - it's not a "real" car, it's a toy car, and it requires special driving to drive it.

That being said, while I've experienced the problem in my 2009 Prius, I've payed attention to it and it does seem like you lose a foot or two at most, and it seems like if you press harder on the pedal you still have some kind of brakes. It "feels" like the car lurches forward, but after paying attention for a while it may well be that it simply stops braking as well during that period.

I don't know for sure. It sure seems like a dumbass design.

P.S. Someone asked if other hybrids had similar behavior - I know the Ford Fusion had something similar happen, they say they fixed it when consumer reports discovered it.

 

New guy here,

I really like my Prius but some of the responders here sound like Toyota brainwashed them. I think some people here would marry their Prius is they could. You shouldn't have to learn to anticipate lurching or Prius quirkiness to drive the Prius. It should be as simple as you apply brakes and you start to stop, no guessing that your going to jump forward or feel like your jumping forward.

Who knows what really happened that day of the accident, even the original poster is fuzzy on the actual speed but I will tell you I have had the car "lurch" or suddenly accelerate for a "second" while driving onto a uneven road surface from a smooth paved road surface. I was turning into a driveway and my speed was less then 10 mph when the car felt like it was being pulled forward by an invisible force. It only lasted a second and me hitting the brakes I think stopped it.

It has only happened once, we shall see what happens when snow falls here in the Winter.

 

Here's a reminder of the Ford problem. Lots of similarities.

Report: Ford issues TSB fix for brake pedal on Fusion Hybrid models [w/video] — Autoblog Green

 

Yes, other hybrids exhibit this behavior. Other non-hybrids also. The FJ-40 ABS system does exactly the same thing, with nary a hybrid component in sight.

Tom

 

Ok so i checked the manual and there's nothing that states that you need to anticipate a boost forward while applying the brakes. I'm glad we got that out of the way.

Convincing priuschat there is something wrong with the car is like trying to convince Charles Mansons follwers that there was something wrong with the guy. Not gonna happen. Let's call a spade a spade here.

 

James Stakes' lawyer will glad to take your testimony

 

Yes, I think it does apply to a myriad of cars/brands - 20 years ago, ABS and particularly VSC were options/luxuries. Nowadays, they're far more commonplace.

And it IS extreme with the Prius if you haven't gotten the ABS ECU recall fix done - and has to do with the transition from regen to friction braking, and resetting the braking level afterward. The problem relates to how strong/fast the friction brakes kick in when ABS/VSC are triggered, and afterward, resetting regen braking to where you had it before (instead, it's much, much lighter). The "workaround" is to either push a lot harder on the pedal, or take your foot off and reapply the brakes to reset everything. (and that's assuming you only hit one bump...)

I haven't attempted to recreate the problem since getting the fix, but what the fix is supposed to do is kick in the friction brakes sooner/stronger, and afterward to reset the regen braking closer to where you had it before. Reports are that the first half of that (friction brakes) definitely works, the second half is improved but still not exactly perfect.

But even so, going over a lot of bumps (especially on a long corner) is going to make the ABS and VSC both work overtime and give you less overall braking than a car with "old-school" brakes (which could skid or roll over instead).

ABS isn't designed to stop you sooner - it tries to, but the main purpose is to give you more control. A lot of people complained about this when ABS first came out, but that's how it works and it's safer - overall - than an uncontrolled skid. VSC makes some additional sacrifices to stopping distance in order to significantly reduce the risk of rollover.