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Toyota Prius Brake Problems

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Comments

  • 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: 317
    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 http://www.csgnetwork.com/stopdistcalc.html 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. AND...it 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 http://reviews.cnet.com/coupe-hatchback/2005-toyota-prius/4864-10867_7-31352228-- 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.

    image
  • 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:
    http://pressroom.toyota.com/pr/tms/toyota-reports-december-and-2009-150487.aspx

    Bob Wilson
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