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Toyota Prius Brake Problems



  • I had a similar problem. Turned out to be a faulty skid control computer-$2200 and scared the [non-permissible content removed] out of me! I also am looking to dump mine. Loved it to this point, but just feel unsafe now. Anyone else had this experience?
  • Please describe the incident. Many are probably curious. Thanks.
  • fraz1fraz1 Posts: 1
    I have had the automatic acceleration problem 3 times. Two times when I was driving it and 1 time when my husband was driving it. We do have documentation on this from toyota. The brakes would not work in normal driving conditions and the accelerator would not stop accelerating. this was not a floor mat problem. I tried to pull the accelerator up but it made no difference. The documentation was about a year before anyone mentioned it in the media. Toyota did not want to document this for me but my husband went back and insisted. Some of their salespeople are telling people that this is basically a hoax. Beware.
    I have always had success with our other toyotas but would not even want to sell this prius to anyone for fear of them being in a serious accident. I do not want someone else's death on my conscience.
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,048
    You should post your experience in

    toyota on the Mend in 2010

    toyota halts sales

    Many people there are debating whether the problem with acceleration and braking failure is real or not.
  • Yours would be a first -- a combo of "automatic accel." and nonworking brakes. I can't figure the probabilities, but they have to be on the way to infinite, as I think those two systems are not linked. What year Prius? Could you please tell us more detail on both the acceleration and braking incidents. I don't mean to pry, but it is always helpful to see if there are any parallel's w others' experience. Also, the self-serving dealer aside, have you reported this to Toyota Motor Sales USA, Toyota corporate (Japan), NHTSA? I think at all three of those, you would get maximum attention and they would want to inspect your car. I appreciate your concern about selling it to anyone.
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,048
    >Toyota did not want to document this for me but my husband went back and insisted.

    That resistance to documentation is what many people seem to have experienced through the years. That's not a good trait in a car company.
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,048
    >Yours would be a first -- a combo of "automatic accel." and nonworking brakes. I can't figure the probabilities,

    I believe the two are related. The computer controls the regenerative braking just as it controls the acceleration or doesn't control the acceleration in this case. The computer controls the switch from regeneration braking to applying the hydraulics brakes. That switching process with its noticeable, and dangerously long in some cases, lag is what a few people have complained about and has been reconfigured on the newest of the Priuses.

    However, the computer gone crazy and giving full acceleration probably isn't goiing to be a computer also correctly apply regenerative braking nor will it apply the hydraulic system correctly.
  • 07prius07prius Posts: 10
    edited April 2010
    "I had a similar problem. Turned out to be a faulty skid control computer-$2200 and scared the [non-permissible content removed] out of me! I also am looking to dump mine. Loved it to this point, but just feel unsafe now. Anyone else had this experience?"

    Yes many times...don't like the TRAC control on my Prius one bit.
  • wwestwwest Posts: 10,706
    edited April 2010
    " I think those two systems are not linked..."

    Not linked...??

    Without any doubt even closer than indentical twins still in the mother's womb.

    More like a "deadly embrace" between the two systems.
  • wwestwwest Posts: 10,706
    "...don't like TRAC control.."

    And yet it has probably already saved you from at least one accident or injury.

    No one should ever drive a FWD or F/awd vehicle without these life-saving "nanny" features fully active. If you're an inexperienced wintertime driver, or an idiot, they might even be of great help with a RWD or R/awd.
  • 07prius07prius Posts: 10
    "...If you're an inexperienced wintertime driver, or an idiot..."

    Really? Funny, in my 1982 Mercedes 240D, I never had any of these issues and there were no computers in that car, nor was I ever in an accident in that car. Having the TRAC control kick in when driving 25 mph on perfectly dry, smooth pavement is NOT the kind of "nanny" feature I want. Save your patronizing for someone else. I don't respect people who use the autonomy of a forum to belittle others.
  • wwestwwest Posts: 10,706
    Mercedes doesn't build FWD vehicles.
  • whitey9whitey9 Posts: 138
    Your '82 made 60Hp and revved like a freight train. If you had a manual trans, you were better off in the snow. Altho' shifting down to low helped on the auto. trans.
    There can be little doubt that today's car/engines can easily overcome the average driver's "skills".
    We are learning more and more about faulty algorithms instilled in control units on our cars/trucks/SUVs. ( Lexus GX 460 )
  • smadisonsmadison Posts: 3
    Definitely hitting an oldie but goodie here. Not to beat a dead horse, but this thread came up as I was investigating a problem my daughter had recently with her 08 Prius and wanted to jump in with our details:

    First off, a few caveats - I'm an Engineer, and have approached this in a typical engineering fashion. I'm not an automotive engineer, but I did do quit a bit of MechE studies and earn my living as a Software Engineer, and I've got a pretty good handle on both the mechanical and electrical diagnostics. In addition to the Prius, which my daughter drives, we've got a VW Bora, an Audi Q7 and a Porsche 996, and I'm constantly tinkering with all of our cars to find out what makes them tick and how to make them tick better.

    On Saturday, 24 April 2010, my daughter was driving over Hwy 17 to Santa Cruz, CA when she rounded a corner and executed a panic brake due to completely stopped traffic. She was able to keep the car under control and avoid collision. ABS likely was engaged. It's likely that the Stroke Sensor failed at this point. One or more calipers continued to be engaged after she stopped stepping on the brake pedal. She drove another several miles in this state, and experienced brake fade when she tried to come to a stop at a traffic light. When she finally pressed fully on the brake pedal, secondary braking was engaged and the wheels locked. She fishtailed, but was able to maintain control of the vehicle and avoid collision. She immediately parked and called me. Vehicle was towed to nearest Toyota dealer. Diagnostics indicated a DTC C1247 Stroke Sensor Malfunction, but upon electrical reset all mechanical functions resumed normally.

    Brake failures are pretty frightening, especially when it's your inexperienced teenage kid behind the wheel. However, I suspect that failures of this nature are fairly endemic to all regenerative braking systems. No extent of mechanical controls would be capable of balancing the engine and brakes, so you've got to trust these things to a computer. And I can guarantee you that all software has bugs, especially around edge conditions. It's simply impossible to test for everything, all you can do is document and learn from your field data.

    That being said, I would certainly hope that these situations have been heeded and improved by Toyota. I'm reading stuff here that's five years old, which what appear to be ample field reports. Toyota needs to step up to the plate and take immediate action on this stuff, and stop dismissing it as Edmunds/GM propoganda.
  • betsyrbetsyr Posts: 5
    My prius is still surging even after getting the fix. It spends most of it's time in my garage since I have two young children and don't feel like it is safe. Today I sent yet another complaint about yesterday's surge to the NHTSA and decided to search to see if others are still having the same problem. I found many complaints post fix.

    We tried arbitration, but got nowhere. We have taken it in multiple times. I know Toyota maintains that it is safe, but I don't agree. I have had several people explain the way the brakes work, but a surge is still a surge. I drive slowly and take my foot off gas way before stop light, but what I can't control is when on a fast road and am cut off and then the person slams on their brakes. I tried to trade it in, but I will lose more than $12,000 on a car that is less than a year old. I know cars depreciate about 20% in the first year, but that is almost a 40% depreciation. Now I am stuck with a car that I don't think is safe! I am calling everyone from media to senators and hope that I get some traction. From NHTSA and other forums I know that I am not the only one experiencing this problem. One way or another this issue must be resolved!
  • wwestwwest Posts: 10,706
    Life is a series of compromises.

    You wanted a hybrid, highly fuel efficient, car. That can't happen without regenerative braking to recover energy that would otherwise be lost to heating of the brakes. So the frictional brakes MUST be disabled at times, random times insofar as you are concerned.

    As far as I know there is simply no way to make an easy and smooth transition, certainly not in all circumstances/situations, from pure/only regenerative braking to partial or even full frictional braking.

    And by the way, what you are experiencing is NOT a SURGE but a slight lessening of braking effort. I just drove a 2010 Sienna for a full week and the forward lurch/"surge" due to the coastdown upshift after the engine fuel-cut period is just as noticeable in the Sienna as in the Prius.

    My '01 F/awd RX300 has very much the same coastdown "upshift" lurch/"surge" as the speed declines below ~35MPH or ~10MPH. I noticed it at first, shortly after I purchased it new, but nowadays I find I must pay close attention in order to take note that it remains.
  • stevegoldstevegold Posts: 185
    I have a 2004 with 60,000 miles and have never had anything but a very slight surge.
    The 2010 has disc brakes frond AND rear but that should not cause your problem.
    Bring it to Don at Bighorn Toyota in Glenwood Springs, Colorado and he'll fix it for you.
  • wwestwwest Posts: 10,706
    edited June 2010
    The 2010 Prius had a serious firmware design flaw wherein the ABS would "signal" the regenerative braking system that since wheelslip had been detected only frictional braking could, was to be, used. The problem was that somewhere in the back and forth communications between the two ECU's a disconnect occured and although regenerative braking would be discontinued accordingly frictional braking would sometimes be delayed, sometimes indefinitely, coming online.

    Not just a slight lurch but seconds or more of virtually no braking effort.

    Scary moments resulted.

    Once you have endured a few of those moments even any little bit of brake "fade", "slight surge", common to the Prius, becomes a heart in throat event.
  • agnostoagnosto Posts: 205
    Not a single issue after over 1000 miles in ODO and I am enjoying every bit of the smooth and safe driving of this real cutie... 2nd tank with over 610 miles and 68.5MPG computer calculated... wow, what an awesome vehicle Toyota has built...
  • john1701ajohn1701a Posts: 1,897
    >> Not just a slight lurch but seconds or more of virtually no braking effort

    700 milliseconds.

    Stop exaggerating.
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