braking in reverse

I had the jerky brakes problem once when I was going forward about to turn into my driveway (about 200 miles on the car). I had read of the problem in reverse before. When it started I was very carefull with the pedal pressure but it continued. I pumped the brakes a few times and the problem was gone. I have not experienced the problem in reverse. I have about 450 miles on the car now.

 

can anyone reproduce the problem and how do you do it? i'm taking it to the dealer tomorrow to have them check it out!

 

Unfortunately (?) the problem is intermittent; the type that all mechanics hate. If it were easily reproducible it would most likely be a thing of the past by now. I figure it can't hurt to mention it to the dealers though.

 

it happened to me again while backing out of my parking spot. i tried to reproduce it afterward but could not get it to happen again. i have 3.2k miles on the car so far. this was on a cold engine. i wonder if it's a brake controller issue (the friction brakes are freaking out or something, like all-or-nothing; maybe it's a boundary / variable overflow issue with a variable or a state machine jumping to the wrong state).

 

mine's at the dealer waiting to be checked out! hope everything's ok...

 

My brand new 2010 prius does this occassionally too. My driveway is on a hill and about every third day when I go to back out of the driveway the brakes jerk repeatedly and there is no way to control my speed. I also have experienced a very concerning problem when I am driving and then start to brake-- occassionally there is a delay of a few seconds before the brakes engage. It feels similar to the feeling of sliding on ice for an instant. I am taking my car into the service center at the dealership where I bought it on Sept 14th, and will report back.

 

48/50 and dhc -- please let us know what your dealer find or say about this!!

Thanks!

 

I've experienced this a few times in reverse; yesterday was the first time I experienced it going forward. Possibly useful (but more likely extraneous) diagnostic information:
- It was after sitting for just a short while (run into the store for a second)
- The brake pedal felt hard as a rock--like in a typical car when you pump the brake while the car is turned off.

It went away when I put it in neutral and stood hard on the brake--do not know which did it. It is a disconcerting experience, even if only because you don't know why it does that...

 

hey maggie,

i talked with the dealer yesterday and they were able to reproduce the problem. apparently, when you reverse on a slope the brake assist kicks in which gives you that epileptic seizure the car gave me. i think it's some sort of brake protection when you're on a slope. however, there are people on the forum that reported it happening on level ground and when driving forward for that matter. the techs at the dealer sent an inquiry to toyota to determine if it's an actual computer glitch or if it's in the norm. i'm looking into returning my 2010 back. i've read too many problems on this forum to convince me to bring it back. i don't mean for this post to sound negative....i'm just bummed because i really love the car...

 

Thanks for reporting back. I have used the Hill Assist - when you're hanging on a hill, and depress the brakes to the floor, the Hill Assist engages and you'll see a light on your dash. it 'holds' the car on the hill until your foot gets to the accelerator so you won't roll back. This grabbing didn't feel anything like Hill Assist, and you don't have to depress the brake all the way to experience it.

More importantly - I'm sorry to hear you're considering returning the car. I think the first year of any new generation car will uncover bugs here and there. This is the only one I've exerienced, and it does not overshadow my overall satisfaction with the car. Please reconsider. A group of enthusiasts like this will nit-pic their subject to death. Nevertheless, I, for one, think is a remarkable technology and for reasons ranging from saving $$ to saving the planet, to just finding it fun to drive, I'm a full-on Prius fan now. Hang in there - its an awesome car!

 

I don't see the problem as a danger unless it happens to someone braking at 50 mph. A few have reported it happening while in Drive, but if I'm understanding them correctly it's when they're pulling away from a stop. Not that this makes it ok, but so far from what I'm reading it doesn't sound like too hazardous a safety issue.

I hope Toyota can get to the bottom of it and issue a fix.

 

I agree, as I've experienced it, it has been what I would characterize as a mild nuisance. I would, however, barring a fix (which would be preferable), like at least to know what is actually causing it. That is just how my mind works--if I understand it, I'll be more confident that it *won't* happen at 50 mph. Which would, indeed, be an eye-opening experience.
T

 

This forum is such a great resource!

I, too, have experienced this braking problem while moving FORWARD. I've had the car for less than two weeks, 400 miles. This has occurred once, so far, after turning off the car briefly to fill up the gas (my first fill-up!) The problem seemed to correct itself after a few lurching stops/starts. I'm hopeful (though not optimistic) that this will be an isolated occurrence, but it sounds like something we need to pursue with Toyota. By the way, my 2008 Prius has never experienced this problem.

 

Yes, I had exactly the same thing happen. With the engine running at quite high RPM I was not game to take my foot off the brake. Fixed the problem by shutting off and restarting the Prius.
Scary.

 

Tossing my cap into the mix: currently at about 2500 miles, my Prius has done the reverse jerky brake thing about five times. Level ground, hilly, seems to make no difference.

Glad to know it's not all in my head--or foot.

 

It happened to me again last night while backing up on a slight decline. It had not happened since the first couple weeks of ownership. I took delivery 7/8/9. I did not try to put it in Park or anything else to reset it but I will try something if it happens again.

 

Happened to me again yesterday coming out of my flat driveway. This time I paused, pushed the brakes to the floor (as other here have suggested) and heard a sound like air escaping from the brakes as I pressed the pedal. Does this mean anything to anyone?? The grabbing was lessened, but not eliminated. So I stopped again and put the car in Neutral for a second, then put it back in Reverse and gripping was gone.

So... are you all sick of this subject, or does anyone want to toss out another explanation??

 

I'm sick of the subject AND I'd love to toss out an explanation. Only I don't have one I really do wish Toyota would address the issue though. I check TIS once a week or so, but no bulletins about it so far.

 

I experienced this today backing out of my driveway. I tried shifting into both neutral and park and neither fixed it. It didn't go away until I moved into drive.

 

Knock on "wood" it has not happened to me once yet. I have a sloped driveway, nothing yet. OK so it's only been about 3.5 weeks, but some posts have seen this early on.

I have not seen any Technical Bulletins and the Dealer I was just at to pick up my Cargo Mat, I spoke to the Service Dept about it and he said they have had no known complaints. He did look in the computer..so I am sure he looked at some records...

I am starting to wonder if this has anything to do with the way people leave there vehicle, meaning, everyone who has experienced this are they pushing the PARK button when parking before turning off, or letting it go to PARK in the Auto format, by pushing the power button? Are they waiting a 15 seconds before backing up, giving the systems time...there's something that's a fluke with this, since if it was across the board to all drivers, I would think it would be a defect and recall process. Have we looked at a specific model to tell if it's related or option group?

I agree it's getting old and we need a good definitive answer...