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Toyota Prius Brake Problems



  • wwestwwest Posts: 10,706
    That rachet lock on the foot operated e-brake can be easily disabled.
  • Re: "That rachet lock on the foot operated e-brake can be easily disabled"

    Thanks. Can I make it user choice? Using the parking brake feature is nice, and apparently regular use of the Tacoma parking brake is necessary to maintain it in a functional state (keeps the lubrication moving in the mechanism)
  • whitey9whitey9 Posts: 138
    VSC ( Vehicle Stability Control ), TRAC ( Traction control system ), ABS ( Anti-Lock Braking System with Electronic Brake Force Distribution ), and BA ( Brake Assist ) all come standard equipment on '10 Priuii.
    Not just ABS like on older cars. The affect is completely different that just plain-old ABS. There is no basis for comparison.
  • whitey9whitey9 Posts: 138
    You drove a Tacoma with a hand-operated emerg/park brake? I am surprised at this developement. Generally speaking, hand brakes are generally on smaller, lighter ( cheaper ) cars/trucks.
    Some cars come with foot applied/hand released e-brakes. Even then, during driving and braking, one must use a hand to keep the brake from staying engaged.
  • monte8monte8 Posts: 75
    "There is no condition known to man wherein Anti-lock braking will not extend your stopping distance. "

    Not correct. Testing has shown that ABS will extend braking distance in only two circumstances: 1. Loose gravel; and 2. Loose/soft snow. Stopping distances were longer as compared to braking by a very skillful professional driver (yes, I know, we all are better than average drivers). ABS will stop in the same distance as the skillful driver when the road is 1)dry; 2)wet; 3)ice covered; and 4)covered with compacted snow.

    Remember that maximum braking deceleration happens not with the wheels locked up, but with 5% rotation.
  • biomanbioman Posts: 172
    I called my Toyota dealer Friday, 2/19/2010, and asked for an appointment to have the ABS software update on my 2010 Prius. I was expecting a runaround, and/or a bunch of excuses as to why the update could not yet be performed. What a got totally disarmed me. The service advisor was pleasant and informed me that I could have the recall performed at a time I choose. So, I picked Friday at 10:00 AM. I arrived at the dealership, Newark Toyota World in Newark, Delaware, at 10:00 AM and by 11:15 AM I was on my way home. My ABS ECM flashed and my car washed. Could not ask for better service.
  • I have read many posts about the momentary loss of braking occurring after driving over a pothole or bump in the road. In my case, I have test driven my Prius on smooth, paved roads, driving 25-30 mph, and then "standing" on the brakes. What consistently happens is the ABS light flashes and I come to a rolling, seemingly extended stop. I have never rear-ended another car before I had my Prius (I have been driving for about 8 years - not very long but long enough). Several weeks ago, I was driving about 35-40 mph in a 45 mph zone, and as I never tailgate, I was not tailgating the car in front of me. This car came to a sudden stop, as the car in front of him had illegally stopped to let a car waiting at a stop sign into the road, which was a main arterial and had no stop sign or light. I had been watching the road carefully as there had been a couple sudden stops in front of me as I was driving. I was still at least 40 feet behind him. I immediately slammed on the brakes, yet my Prius came to a rolling stop, and I rear-ended the car in front of me. I only dented his rear bumper, and dented the front bumper and hood on my car. It just seemed like it could have stopped sooner. I have since read that in such a scenario, you can push the gas pedal and brake pedal simultaneously to the floor to achieve braking without the ABS system kicking in. If that is the case, then why is this not pointed out to the consumer beforehand? I have read alot of message boards online that talk about the "quirks" of driving a Prius - it seems that new Prius owners should be educated about such quirks for safety reasons? My previous car was a 1982 Mercedes 240D. I was completely unprepared for what I experienced. :sick:
  • roho1roho1 Posts: 318
    Sorry for your accident. At 35mph you are traveling at 51 feet per second. So if you were 40 feet behind him there is no way you could have stopped in time considering driver reaction time and braking distance required.
    I think we all underestimate the gap we really need to stop safely.
  • I have a 2010 and was told by my dealer last week that my car has it--brake override--but it only kicks in at 30 mph and above.

    I have not tested.

    I cannot find it in my owners manual, on any Toyota official site or any other car site, in any media story, or in conversation w other Prius owners. I doubt it is true.

    If anyone is sure any year Prius has brake override, please tell me. I am a bit hesitant to try it because, among other things, I do not want to damage the car.
  • 07prius07prius Posts: 10
    edited February 2010
    Re: Post #198: "Sorry for your accident. At 35mph you are traveling at 51 feet per second. So if you were 40 feet behind him there is no way you could have stopped in time considering driver reaction time and braking distance required.
    I think we all underestimate the gap we really need to stop safely."

    There are too many subjective elements I think for anyone to say that there is "no way" I could have stopped in time. I have also used the calculator on which shows that it should have taken me 19.78 feet to stop. Nonetheless, the real issue is that after testing it as I described above I have real safety concerns, and to me it is not as important whether or not I was actually at fault in that accident - I have real concerns that I hope to have addressed, as I have a 93 mi commute and at this point do not feel safe driving my '07 Prius. BTW, I have nothing against hybrids or anything that can help save our planet - that is the whole reason I owned an '82 Mercedes 240D as I could use biodiesel in it (speaking to those who comment that there is some conspiracy against Priuses/hybrids/whatever nonsense).
  • I don't think you used that calculator correctly. To get 19.78 feet as a stopping distance you must have plugged 35 into the km/hr field. If you put 35 into the correct mph field you get a stopping distance of 51 feet which seems much more reasonable. doesn't include driver reaction time.
  • You seem to be correct; it looks like I did use the formula incorrectly. In any case, as I mentioned, that is not the main issue I am addressing.
  • Interesting message post from 2.html?ord=creationDate+desc&tag=rtcol;uo:

    ""High Rate of Low Speed Brake Failure in 2004-2009 Prius"

    by ganderc on April 7, 2009

    Pros: Great car except for the brakes.

    Cons: Has a rate of low speed brake failures 31 times that of a traditionally-braked car (Corolla). Many result in rear-ending the car ahead with no injury.
    Summary: I read that they redesigned the braking systems for the 2010 Prius. That appears to be Toyota's response to the fact that the U.S. Generation 2 Prius (2004-2009) has had low-speed brake failures reported to the National Highway Traffic Safety Administration (NHTSA) at 31 times the rate of such failures reported for the 2004-2009 Corolla, which of course has traditional brakes. Many of the Prius low speed brake failures were in low-speed city traffic, resulting in rear-end collisions without injury. It appears that the several computers that control the complex braking systems were too busy calculating the most efficient way to apply the brakes, and did not get around to actually applying them, until it was too late. Toyota never took responsibility for the problem, but the 2010 redesign indicates they were aware of it. Unfortunately, the NHTSA never initiated an investigation despite the extremely high rate of failures. The detailed failure reports ("complaints") are available to the public on the NHTSA website. The details are these: To April 2009, 2004-2009 Prius has received 44 complaints of low speed brake failure. 2004-2009 Corolla has received 7 complaints of such failures. Given that at least five times more Corollas than Prius were sold during 2004-2009, 44/(7/5) = 31 times the rate of brake failure for the Generation 2 Prius."
  • bwilson4webbwilson4web Posts: 80
    edited February 2010
    You quoted a message someone had posted in a review thread.
    Where is the source data for this obvious nonsense?

    The problem is anyone can post a message saying any nonsense they
    wish. Don't bet your credibility on "ganderc on April 7, 2009" who appears
    to have made something up without citing a credible source.

    Bob Wilson
  • revitrevit Posts: 476
    Here you go....

    Answers to Questions About Prius and the Toyota Recalls

    Q. What is the problem that led to the Prius investigations?

    A. The investigations focus on a new version of the antilock brake systems on the 2010 Prius, which was introduced in Japan and the United States last spring. There have been 124 reports of problems in the United States, and 77 reports in Japan. The problem does not appear to affect earlier versions of the Prius because the brakes were redesigned for the 2010 model.

    In a statement, Toyota said, “Some customers have complained of inconsistent brake feel during slow and steady application of brakes on rough or slick road surfaces when the antilock brake system (ABS) is activated in an effort to maintain tire traction. The system, in normal operation, engages and disengages rapidly (many times per second) as the control system senses and reacts to tire slippage.”

    Owners are reporting that the brakes fail to work immediately when the car is on a bumpy or slippery surface, or when it drives over potholes. Toyota said Thursday that it had already identified the cause of the problem and corrected it on cars built since January. Toyota officials in Japan said Friday that the company was considering a recall of 103,000 new Priuses in the United States and 176,000 in Japan, but that a decision had not yet been made.

  • BWILSON--I appreciate your effort, but your message confuses me. I was aware of the problem, which you describe, that led to a recall. I had the recall fix at my dealer on February 15 via a software flash upload. Your context seems to be of a recall yet to be announced.

    Are you referring to yet another aspect of the brake complaint on 2010 Prii? I bought mine on December 12--and am generally happy with it.

    Also, after listening to Mr. Toyoda's and Mr. Inabe's Congressional testimony last week, I presume that we will offered the installation of brake override--without the formalities of a recall.
  • I called my dealer and got an appointment the same day - my computer has now been reflashed. Motivation? After feeling the symptoms just once since I got the car last August, this past Friday I felt it twice. I wish I could feel complete confidence in the upgrade, since I know that most software is not written from scratch but modified from previous versions, and I am convinced that eventually Toyota will need to fix the problem with the previous brake software in the 2005-2009 cars. Will that problem still be in my Prius?
  • wwestwwest Posts: 10,706
    edited March 2010
    Your Prius, any Toyota, or Toyota "like" HSD systems have BTO by default. When you apply the brakes the HSD firmware is designed to enter regen mode. It is not possible to have regen active AND simultaneously DRIVE the wheels. Well, maybe the F/awd RXh or HH with 2 "drive" channels.

    While it is possible to specify firmware operation that would give priority to the gas pedal position over regen braking that is NOT very probable. That would not only be a serious flaw in the design but would border on intentional, criminal, action.
  • 07prius07prius Posts: 10
    edited March 2010
    bwilson4web: Why does your point have to be made in such a disrespectful way? My goodness, would you speak to me this way if we were talking in person? Right or wrong, I have been very respectful in my posts and expect the same in return. I am not betting my credibility on the review I posted...which is why I called it "food for thought" as opposed to "hard facts." What I experienced is real; I only said "40 feet" in my OP as a gross estimate; in truth I may have been further away, but I cannot be sure, which is why I said from the get-go that I wasn't making a claim that I was not at fault. The '82 MBZ 240D I drove for the past few years had quite a long stopping distance, but I knew what to expect, and never rear-ended anyone in it. I did not realize that the post would be dissected and discredited right out of the gate. I guess I am the kind of person who tries to fully understand someone's point of view before seeking to invalidate it.

    Thank you to those who are respectful on this and any forum.
  • Look, I'm sorry that it came across so harsh but it has to do with citing credible sources. Our local newspaper has a letters to the editor section and every now and then "people not in touch with reality" post complete nonsense. If I were to cite their letter as a source, any and everyone would be right to condemn me for introducing a bad source. Remember, even fibbers can post.

    If you go back to that original source, you'll notice I replied with the actual ratio of Prius and Corollas for those model years and the ratio is ~2.6 to 1, not the '5 to 1' ratio used in his numbers. If he can't get the ratio of cars in that model year right, how are we to trust his other numbers?

    Understand he may be right about the counts of "reports" but look at his own numbers:

    44 - Prius
    7 - Corolla

    The problem is 7 is not statistically significant. It is too small to draw any useful conclusions. So his ratio itself is suspect, as well as his counting.

    I won't complain if you 'do the math' other than if I follow the same procedure we come up with different numbers. Then we'll discuss methodology and make sure we are seeing the same data. But as it stands, that source suffers from a major self-evident problem and a factually inaccurate count of vehicles.

    The reason I knew the vehicle count is I've been looking at the Toyota December sales reports for the past couple of years. This has the total number of Prius and Corollas sold:

    Bob Wilson
  • Hi,

    The ZVW30 Prius, 2010-current, has the redesigned brake system and the recent recall to get rid of a rare, brake pause. The NHW20, 2004-09, has not been recalled but there are reports that it has a similar but less severe pause. The NHW11, 2001-03, is my commuting car and none of my tests have replicated the brake pause.

    2010-current Prius - SSC-A0B

    You don't have to wait on a letter or call from the dealer. Call your local Toyota Service Center and schedule an appointment. If the service writer gives you any grief, ask to speak to their manager ... keep going until you get the right answer, "Yes, come in and we'll fix it." Alternatively, call another Toyota dealer or ask them if you should call the local newspaper.

    The problem is rare and intermittent. Probably the surprise, more than anything else, catches folks off guard. Just press harder on the brake and the car stops almost instantly. In the meanwhile, keep your following distance on the long.

    2004-09 Prius

    There are reports but sad to say, I'm not having much luck documenting the pause. I have an accelerometer that clearly showed the ZVW30 brake pause but I've yet to find someone with a NHW20 to test. I may have to rent one.

    We have a poll going on in PriusChat about the brakes and the numbers are:

    55 - Yes, I want it fixed (22%)
    41 - Yes, However it doesn't bother me (16%)
    153 - No, I don't feel my GEN II Prius has a problem (61%)

    So over half don't see a problem. Only 22%, 1 in 4, wants a fix.

    2001-03 Prius

    I have one and following the same protocol as our ZVW30, I can't find any pause in the braking using the accelerometer.

    Bob Wilson
  • sthogesthoge Posts: 28

    Perhaps you could post your general area and someone that lives near you could volunteer.

    I have a 08 Prius and I have experienced the the momentary release of the brakes when hitting a pothole or rough road, but immediately after the brakes grab. I have even hit areas of ice and the ABS has always kicked and assisted in a timely stop. So over all I am more than happy with the performance of the braking system. Although I wouldn't complain if they removed or shortened the momentary release when you hit a pothole.
  • jacquescjacquesc Posts: 13
    I'm not saying you are not being truthful - however, I am saying you must have not take all situations into consideration. If you were behind someone at a safe distance and they slammed on the brakes for whatever reason. Then, you attempt an emergency stop and a bump in the road causes a couple seconds of complete loss of braking... almost guaranteed an accident will occur. The next step (after making sure that everyone is ok) is deciding who's then who is at fault?

    I stand by my prior accusations that the poor engineering of the car is the reason for the accident. Thus, Toyota is at fault for not addressing the problem in the 2nd & 3rd generation Prius.
  • You wrote:

    "Perhaps you could post your general area and someone that lives near you could volunteer."

    I'm in Huntsville AL and had one possible volunteer but he never followed up. So I'm thinking rental car. But I'll need a rainy day for the test.

    The other option is the iPhone and iPod Touch have a built-in accelerator chip. I have no fiscal interest in them but there are at least two applications that record accelerations fast enough to gather engineering data over short intervals. Dynolicious Logger is one I've tested and within short intervals, 30-45 seconds, the data is usable. Unfortunately, I'm see long term drift that limits it to mostly short tests like the brake pause.

    Bob Wilson
  • whitecliffwhitecliff Posts: 2
    edited March 2010
    Well it happened again yesterday. Fourth time on my new (January '10) Prius.
    I was slowing for a turn, going about 18mph and the car surged ahead.
    I thought there was a recall but I still haven't heard anything from them yet.
    Does anyone know if the "flash" worked?
  • If your car was made in the last week of January, it already has the post-recall brake configuration; your dealer will know. Mine, bought Decemer 12 needed the fix and I got it February 15 in a one-hour visit to the dealer. I still have not received paperwork from Toyota Motor Sales USA about the recall, but I did get an email about it from the dealer about a month ago and I immediately made an appointment. The problem it fixes, disconnection of the ABS momentarily when you hit a bump or one or both traction wheels lose road contact, is something I experienced early and got used to. I did not really need the recall because I knew my brake was always operative and I use it automatically in those situations, with no need for ABS support. A couple of times the ABS activated on snow, and I did not like it all, and it did not help (I did not expect it to).
    On the "other" brake issue, my dealer told me in a phone call yesterday that all Toyota hybrids " already have brake override." I think that is not the correct use of the term, because what the service department told me was that the brake pedal always "has precedence" if both accelerator and brake are pushed simultaneously. I think true brake override would mean the engine shifts to neutral when both pedals are pushed, with no need to touch the shift. The dealer is mailing me a 16-page hardcopy explanation of how the Prius brakes work; she said it was technical, but I am very interested in reading it. As far as I know, it is not available on the Web, but your dealer might have it.
  • Your engineering and Prius knowledge is breathtaking. I am no engineer, but I have learned a lot from your posts. Thanks for locking onto this set of issues and letting us learn what you are finding and what the loose ends are. You are helping me retain confidence in my 2010, the quirks of which I have mostly found--I think--and adjusted to. I remain impressed with the car and hope Toyota can manage its way through the current mess with honesty and sincerity. There is a lot of bad information and also disinformation (I sense) floating around.
  • Hi Everyone,
    I had posted a while back about my accident in Dec 2009 that I had with my 2009 Prius, where my brakes failed at a low speed and rear-ended the car in front of me. I've been seeing lately a lot of people noting that 2nd gens have been also experiencing the problems and are upset that Toyota hasn't done anything to find a solution. I am one that is very upset as well. I have brought the car in to be inspected and called Toyota multiple times about my brakes before and AFTER the accident and they keep telling me "there's nothing wrong w/ them" despite almost everyday occurences of going over potholes and feeling that temporary loss of sensation from braking. My favorite was when they were trying to argue with me on the phone what happened- "your car must have slid on something, like ice." <---- Really? I did a walk around my car after the accident.. there was no ice/ no snow/zilch. Your car has a defect!! Oh and my other favorite Toyota rep. telling me to just trade the car in if that's how I felt. Overall, I'm frustrated and don't know what's the next step about this car and how to deal with Toyota...

    So here's my question: Any one aware of any civil action suits involving the 2nd generation brakes? Because I would love to know so I can hop on board and have Toyota solve the problem for the whole Prius line and feel safe driving it again. I've absolutely had it with Toyota right now.
  • whitey9whitey9 Posts: 138
    So why are you still driving it?
  • wwestwwest Posts: 10,706
    "..I was slowing for a turn..." " surged forward.."

    In the circumstance you describe the VSC may have activated as the result of detecting some minor level of understearing/plowing, or possibly even a bit of over-stearing. If you are already on the brakes then VSC activation will sometimes result in "unbraking"(***) one of both front wheels.

    *** Sometimes that might mean an instant disabling of regen braking and the resulting "lurch" forward "seat of the pants" feeling. If the frictional brakes are also already in use then the regen will be disabled along with unbraking of the frictional brakes on one of the front wheels.
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