Toyota Admits Brake Design Problems with 2010 Prius

2010 Toyota Prius

2010 Prius

Toyota acknowledged Thursday that it found software design problems with the antilock brake system on the 2010 model year Prius. The company corrected the problem in Prius models sold since late January. The company said it was still investigating how to inform people who had bought the 2010 model prior to January. Toyota has sold approximately 100,000 units of the 2010 model since it went on sale in spring 2009.

The braking issue is not related to the unintended acceleration problem that recently led to a series of recalls on earlier Prius models, as well as eight non-hybrid Toyota models.

Paul Nolasco, a company spokesman, said the time lag for Prius brakes kicking in felt by drivers stem from the two systems in a gas-electric hybrid—the gas engine and the electric motor. When the car moves on a bumpy or slippery surface, a driver can feel a momentary pause in braking—lasting about one second—when the vehicle switches between the traditional hydraulic brakes and the electronically operated braking system. The brakes start to work if the driver keeps pushing the pedal.

While the Prius braking issue could cause safety problems at high speeds, the common complaint from drivers has been related to the “feel” or “sensation” during braking. A visitor to wrote, “It feels like the car is sliding on ice but only lasts a second then the brakes hold again.” Others have described it as “lurching forward” or an “unsettling experience.”

Toyota said Thursday a software glitch is to blame for braking problems in the 2010 model. In late 2009, the National Highway Traffic Safety Administration started to track reports—so far about 100 consumer complaints—about the 2010 Toyota Prius’s braking performance.

Toyota has not yet issued a recall on the 2010 Prius. The likely fix would be a fairly routine software update. “We would want to be given a little time,” Hiro Yuki Yokoyama, Toyota’s managing officer, told reporters.

The Prius is Toyota’s third best-selling model in the United States.

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  • Mr.Bear

    Toyota did not admit a “brake design problem”. That makes it sound like a physical design problem with the brakes.

    They admitted that there is a problem with the braking system’s software upgrade they started using in cars in January. I suspect the solution to the problem will be to revert to the pre-2010 software.

  • Joshie

    They knew about the problem and waited to inform customers, and now they’re STILL waiting to recall the vehicles? There goes Toyota’s sustainability/credibility.

  • Skeptic

    This is really, really bad, IMHO. Fly-by-wire with the throttle is bad enough, but with the brakes? Not me, pal. When I step on the brakes, I want the car to stop *even* if some piece of software thinks that’s a bad decision.

    One second, BTW, is 88 feet at 60 miles per hour.

    My opinion of Toyota has dropped considerably with this one (the throttle issue, by comparison, doesn’t seem so bad).

  • AP


    As an automotive engineer (at GM), I can tell you that without an electronic throttle, the whole hybrid system in the Prius would not be possible. The driver pushes on the pedal, and the computer must decide whether to accelerate the vehicle with the engine, or with the electric motors only. If the engine is running, the computer must decide how fast to run the engine and how much to open the throttle, in order to minimize fuel consumption and provide enough power to keep the battery charged. This is what you pay for.

    The same can be said for the brakes. The driver pushes on the brake pedal, the computer interprets this as how hard the driver wants to stop, and applies some combination of the regular brakes and the electric motors (as generators) in order to slow the car (if the battery is already full, the regular brakes might be used alone).

    This all happens very quickly of course, if the software is right. I won’t comment on their fail-safes or testing, since that would be a conflict of interest for me.

    If you like hybrids, this is part of the game. Personally, I like small, light cars with manual transmissions (manual everything, actually).

  • Mathias

    Toyota waited to tell their consumers that there was a safety issue with the 2010 prius until somebody lit a fire under them (Japanese and American Safety Organizations). Last year, i swore by the safety and quality of the 2010 prius as an owner to my peers. Now i am stuck with driving an unsafe car that does not stop when i want it to and i travel a lot.

    I will never buy a TOYOTA (any model) ever again as they are liars, I actually want to sell my unsafe overhyped 2010 prius, don’t know if i will get anything for it now.

  • Nelson Lu

    I will say this: I feel your pain, but I also don’t know how much of this is getting accustomed to the brakes as opposed to the brakes actually having a problem with stopping. Certainly I felt that I had some getting-used-to for my Ford Fusion Hybrid. Now that I’ve gotten used to it, I don’t feel that I have a problem with the braking.

    But I’ll say this: my mother, who had driven a Toyota decades ago, has not gotten a Toyota since, and she argued against my getting a Camry Hybrid. Turns out her advice was right.

  • alancamp

    “Now, the Nikkei newspaper is reporting that Toyota has decided to recall a total of 277,000 Prius vehicles, with approximately 100,000 of them sold in the U.S. market. NHTSA is also investigating roughly 37,000 2010 Prius models already on the road in the U.S. Toyota has not officially acknowledged the recall at this time, but the Nikkei newspaper reported that Toyota will be filing the official recalls with both the Japanese Transport Ministry and NHTSA.”

  • Charles

    AP, I have a question. I assumed that the brakes were only partly fly by wire. I thought the computer would use the electric motor/generator progressively more as the brake was applied, but that at some point the brakes worked on pure pressure. An I wrong about this? If I am wrong, I am going to rethink buying a hybrid.

  • Toyota Driver

    skeptic, if you don’t like “fly by wire” systems, i suggest you don’t get on a plane either, LOL. But seriously, fly by wire systems are generally more reliable than mechanical links.

    Most likely these so call “braking problems” consist of some real problems, some ABS/stability control adjustments, and may even be driver errors. Now that there is so much news about it, there is bound to be a lot of bandwagon reports which may include physiologically induced “incidents”.

    I said it before, and I’ll say it again. No where in the general media has the recall being discussed objectively by mentioning statistical significance of these incidences. One would have to ask, how “normal” are these incidents compare to other vehicles across the board? The tabloid reporting style is irresponsible and sleezy to me. Perhaps that is the only way the media can survive these days…

  • Norman

    GO! chevy volt

  • Anonymous


    I hope there are more people like you to lower the demand for Prius… May be I can finally get a good deal!!!

  • Toyota Driver


    Looks like you spoke too soon… Ford just issued a statement about their problems with braking too. Your mother should have advised you to take transit.

  • Nelson Lu

    Toyota Driver, as I wrote in the other thread, what I experienced matches with what Ford’s press release says, actually, and I do not view it as a safety problem myself since actual braking ability seems to be unaffected. But I’ll take the car in for reprogramming when the letter comes in the mail.

  • AP

    Charles, your question about the brakes being “only partly fly by wire” is a question I’m not completely sure how to answer.

    In a typical car with anti-lock braking (ABS), the pedal applies hydraulic pressure to the brake calipers. If a tire starts to slip, the ABS system relieves pressure to that brake to keep the tire rolling and producing near its maximum braking force. If the ABS system goes bad, the fail-safe is that the hydraulic brakes still work, but the “anti-lock” aspect is gone.

    In a hybrid with re-gen capablity, I’m not sure what the fail-safe is. I would assume that the default is still the hydraulic brakes, and that the computer has to intentionally relieve hydraulic pressure when it wants to use the electric motors to re-gen brake.

    From what I’ve read on-line, it sound like the Prius issue is a misinterpretation of a temporary slip of a tire, from hitting a bump, as being slip from a slick surface. The system then intentionally reduces braking to avoid lock-up, delaying hard braking until it “figures out” that the surface isn’t actually slick.

    Note that normal ABS systems have to make this distinction also, and so could be prone to the same issue. The fact that this is happening on a hybrid could be coincidence.

    The fact is that most (maybe all) modern cars also have electronic throttles, which is largely to produce better fuel economy. The driver’s “throttle pedal” position is interpreted as an “acceleration demand,” and the computer runs the engine in the best way to produce that much power with minimum fuel burned.

    Both of these systems are a necessary imposition on us if we want to save fuel and generally increase braking safety. Occasionally an issue like this will crop up. Personally, I think most people are over-reacting to this aspect of this.

    As a GM engineer, I think Toyota’s bigger issue is the way they’re handling this, especially with our “more emotional than logical” media. As many others have found out, it’s best to be up front about these things and put them behind you. Japanese businessmen tend to be less vocal, so perhaps they didn’t want to raise any issues until they were absolutely sure they had to. Unfortunately, this results in a constant dribble of info to the press’s feeding frenzy.

  • DownUnder

    You’re right. The issue is how Toyota handles this. They should have come clean earlier. This is a valuable (and painful) lesson for them. I think they will recover (slowly) after this setback.

  • MOU

    Yes bad that Toyota knew about the problem and secretly fixed it end of January – very bad for their reputation and creditibility. But still better than Ford: They have the same issue with the hybrid breaks and fixed secretly back in October without telling customers who bought their care before that fix:

    Both companies should have recalled their cars the moment they were aware of that problem.

  • Mathias

    Why dont you buy my Prius, if you are serious, we should talk. I think you might have not read about the braking issues but you know IGNORANCE is BLISS

  • Samie

    There are several issues that must be rationalized from this.

    1. All manufactures are adding more and more electronic devices like computers, processors, and sensors to their vehicles. So one should naturally expect these types of problems as we shift to more processing development than traditional mechanical engineering. (But we can not make up for those who have lost their lives over these technical issues/problems)

    2. Toyota is a big time auto-manufacture. Quality has gone down slightly in recent years and they have not been exposed to major problems from past mishaps.) eg. Ford with the Escort, GM with the Geo Tracker, or even the Caviler/Cobalt where it was common to have parts fall off. So the point is almost any big time manufacture at some point will have these problems. I would argue that GM’s mishaps in the 70’s to mid 90’s cost them major market share and until recently one could question their commitment to quality and safety.

    3. Government agencies like the National Highway Traffic Safety Administration often are timid and not proactive in investigating legitimate claims of safety. Any real claim should be flagged and reviewed later in a manufactures production process not a one moment in time approach like we see. The National Highway Traffic Safety Administration now is trying to act tough in front of cameras to avoid congressional investigations and public concern. It may be the times we live in but there always needs to be mechanisms in place that allow Federal Agencies the leeway to look into matters that conflict with those interests that they are trying to regulate.

  • Anonymous

    Mathias, if your car is in good condition and you are will to let it go for cheap, we do need to talk

  • LP

    I have a 2010 Prius bought in June, 2009 and am looking for reassurance. I had one bad moment when I was breaking on snow and the car was sliding. I was on an incline on the street coming out of my house and I felt like the car was going past the light and the intersection where there were other cars going across. Could not understand why. I had been coasting and was below 20mph and was not slamming the brakes. I don’t have heavy feet.

    I also feel sometimes like the car starts to speed up for a second or so before it starts to break. That started before the recalls on Prius carpets for years up to and including 2009.

    No, I was not on the accelerator pedal. I take my foot off the accelerator and coast well before I have to break at the light or whatever I have in front.

    So I am following very carefully and am very careful when I have to break. I am going to keep watching and remembering road conditions. I hope we hear soon what is happening.

    I love the car. only 5500 miles on it.

  • toyota driver 2

    We are now on our 8th toyota/lexus since 1983 and now have a 2010 Prius. Happy with all of them, BUT we had problems with 2 Lexus cars: a 1992 SC300 and an early model big Lexus sedan. Both were of the sudden acceleration type, plus the 1992’s last episode was a strange loss of power to a crawl. In all these cases, the dealer’s reaction was “our cars are perfect and you must be crazy”. We left the 1992 on the dealer’s lot for weeks, back in 1995, and they refused do a anything, till we contacted Lexus USA in Torrance. Then they changed 3 computer chips or boards. We had no problems for the 3 more years with that car.
    My concern is that Toyota/Lexus have the wrong attitude: they should listen carefully and investigate each occurrence in detail until they figure out what is wrong. That is the only way to start diagnosing a complex problem. Instead, they tell you they can’t see anything wrong on examining the cars, and that you should just take them home and keep on driving.

  • LP

    From a British article Toyota will recall the Priuses. After that exxperience, I had to drive about 3 miles and I was extremely careful staying way behind other cars and stopping far from the cars ahead of me. I did not know if the issue was road conditions.

    I was coasting down the incline from my house to the light. I coast all the time in all kinds of weather because the light is almost guaranteed red ( 5-way intersection ) with no turn on red. I am in a cul de sac. The length of the incline is maybe 100 yards and it is not steep. But it is steep enough that brakes have to be applied to come to a stop. The car seemed to not want to stop and I was sliding away from the curb. I actually thought it would end up past the lights where cars were going across.

    It was snowing, road was white, not sure if there was ice under it. But I would expect to have no issue if I have been coasting at low speed and am not slamming on the brake. I expected to have good all weather tires. It lasted seconds before I managed to control it and stop.

    I had an appointment, otherwise I would have gone back home.

    I will go with the brake correction for my peace of mind.

  • LP

    From a British article Toyota will recall the Priuses. After that exxperience, I had to drive about 3 miles and I was extremely careful staying way behind other cars and stopping far from the cars ahead of me. I did not know if the issue was road conditions.

    I was coasting down the incline from my house to the light. I coast all the time in all kinds of weather because the light is almost guaranteed red ( 5-way intersection ) with no turn on red. I am in a cul de sac. The length of the incline is maybe 100 yards and it is not steep. But it is steep enough that brakes have to be applied to come to a stop. The car seemed to not want to stop and I was sliding away from the curb. I actually thought it would end up past the lights where cars were going across.

    It was snowing, road was white, not sure if there was ice under it. But I would expect to have no issue if I have been coasting at low speed and am not slamming on the brake. I expected to have good all weather tires. It lasted seconds before I managed to control it and stop.

    I had an appointment, otherwise I would have gone back home.

    I will go with the brake correction for my peace of mind.

  • AP


    It’s hard to say whether your issue would be any different, hybrid or not. If there were ice under the snow, the ABS can only brake the car as quickly as the traction allows. Packed snow also reduces braking ability.

    Also, magazines have pointed out that in DEEP snow, ABS may increase stopping distances, since the quickest way to stop is to lock up the wheels and let the snow bunch up in front of the tires. This doesn’t sound like the conditions you’re describing, though.

    Being a Michigan resident in a hilly neighborhood, I am familiar with the “don’t know if I will make it” feeling heading downhill towards a stop sign, and I’ve never owned a hybrid.

  • Bill Carpenter

    If you like hybrids, this is part of the game damn near everything on these cars are electronic so you must rely on small soldered connections to save your life. Solder is applyed to these circuit boards and connections with heat. Electricity creates three things: light, heat, and a magnetic field. If there is a certain amount of resistance in a circuit heat is created which can easily break a solder joint in the right circumstances. Personally, I like small, light cars, and light duty trucks with manual transmissions and more than one mechincal fail safe.

  • Joan1

    DECELERATION PROBLEM WITH 2010 PRIUS: After stopping or slowing down my Prius has occasionally completely lost acceleration ability, Pressing on the gas pedal, even flooring it, has no real impact. There is an efficiency lag of about 5-6 seconds. Finally, flooring it has some results and the car will slightly move forward until it picks up normal speed. This total to near-total loss of power is very dangerous when trying to enter traffic. The only other person I know who has a 2010 Prius has experienced the same thing, but our dealers (in two different states) acknowledge nothing. ANYONE ELSE OUT THERE HAVING THE SAME PROBLEM ?????????

  • wendy maddy

    My brother Richard Jack Maddy was just killed while driving his Toyota Prius on a rural highway. A truck waiting for him to pass so it could turn left across Dick’s lane suddenly turned in front of him, having been rear-ended by another truck. Dick’s airbag deployed, but he was unable to stop or decelerate, and he was killed outright. The accident report says he lived between four and fourteen minutes. He was stuck in the wreckage for at least three and a half hours before the rescue crew could use the jaws of life to get his body out. That’s probably partially because of the extreme risk to rescue crews from the powerful electrical charge in a Prius. He was just minding his own business, on his way to help somebody, when he died. Toyota knew in 2007, 2008 and 2009, and indeed, from the very first day of production of a prototype, due to testing procedures, that the Prius had a slow brake response time, and why (because of the changeover from one to the other type of braking system at the time of deceleration -hydraulic to electronic), BUT THEY CONCEALED THIS INFORMATION FROM POTENTIAL BUYERS ON PURPOSE SO IT WOULD NOT AFFECT SALES FIGURES. Toyota decided it didn’t matter if somebody couldn’t slow down or stop at once when an emergency traffic situation occurred. Instead of admitting they had an inherently dangerous condition in their autos that would cost lives on the highway, and alerting the buying public about this problem, or fixing the problem in advance, acknowledging they needed to do something differently in order to ensure the safety of drivers of their product, THEY KEPT SILENT AND WENT AHEAD TO PRODUCE INHERENTLY FATALLY DANGEROUS AUTOMOBILES! ANYONE could die behind the wheel of a Prius: take your pick! Either the accelerator can get stuck and speed up to a high speed, or it can be stuck and not respond to taking your foot off the gas and braking, OR your brakes will not react in time to save your life at a high rate of speed, because your car’s braking systems are busy changing over from one system to the other, and so you are literally sliding on ice without any brakes at all while your doom looms ahead of you in the form of another vehicle hurtling toward you while you are completely helpless, trapped in your Prius as your death approaches and it fails to slow down or stop, no matter what you do, because it mechanically cannot obey your actions! Toyota built these monstrosities, these death machines, and to keep sales from hurting their bottom line during the worldwide economic depression, and especially in their biggest market, the USA, DELIBERATELY DELAYED ACKNOWLEDGING AND INFORMING THE PUBLIC AND ESPECIALLY DELAYED INFORMING THEIR OWN CUSTOMERS DRIVING THESE DEATH TRAPS THAT THEY NEEDED TO BRING THEIR CARS IN FOR ACCELERATOR AND BRAKING PROBLEMS. IN MY OBSERVATION, NO DEALER FIX WOULD HAVE SOLVED THE INHERENTLY IMPOSSIBLE BRAKING PROBLEM. THE CAR NEEDS TO BE REDESIGNED TO FUNCTION ONLY ON TRADITIONAL MECHANICALLY OPERATED HYDRAULIC BRAKES, WHICH ARE THE MORE RELIABLE AND CONSISTENT, TIME-TESTED SYSTEM. BUT NOTHING WOULD HAVE SAVED MY BROTHER FROM HIS FATE, BECAUSE TOYOTA NEVER SENT HIM A RECALL LETTER. THEY HAD ONLY BEGUN IN APRIL 2010 TO NOTIFY 2010 PRIUS OWNERS, AND THEY WEREN’T GOING TO GET AROUND TO NOTIFYING THE REST OF THEIR CUSTOMERS, ONE OF WHOM WAS MY BROTHER DICK, UNTIL LATE JUNE! RICHARD JACK MADDY DIED ON JUNE 16, 2010. He would have turned 62 and celebrated his birthday on July 13, 2010. Because of Toyota Motor Company’s overriding and selfish concern for their bottom line, which was very profitable this year for the first time since the US recession, my brother did not get the chance to celebrate his birthday and qualify for his Social Security retirement, a milestone that I happen to know personally he was looking forward to very eagerly for many years.

  • gabriela kalchbrenner

    I own a 2009 toyota prius may 4 2011 had my car in the shop because brake light was on abs &vsc code 1247 was very difficult to stop!!!! today may 9 2011 having the exact same problem!!!! Is anyone having the same problem???? Iam scared to drive!!!! when they tell you they fixed the problem & it happens 5 days later—–whats wrong??????????????????

  • imani1

    I like my Prius 2010 but the misfortune is that I just purchased it in late late 2011 off the floor. I fell in love with it, but now the problem – when I hit a bump I go skidding along as if I’ve hit ice. I called and went into the dealership and found that they claimed to know nothing about what I was talking about.
    I did research and found that this was a common problem on the 2010 model and even the article at the head of this page says ” Toyota Admits Brake Design Problem…” Now how could they not know?
    To complicate matters I took it to the dealer today, May 23, 2012 (I have only 900 miles on my car) and they said they found nothing wrong with the brakes and there was nothing they could do if they could find no problem. Does this sound familiar? It is – one owner traded his car in because of the problem.
    Seems I’m always a late arrival, but I’m terrified of this car. Suppose a little kid runs into the street and I’m coming – hit a bump and the brakes and the car keeps going? A serious possibility??? YES
    So I asked, they did not offer, to please allow them to do a test drive. So that is tomorrow. Hopefully they won’t run over any little kids. Any comments welcome. I

  • Haneesh

    As mentioned as in high speed there may be a safety problem, but it may not be acceptable becoz the hybrid vehicles use the battery power less in high speed that is the technology of hybrid system, so as compared to the ordinary vehicles the hybrid vehicles are similar in high speed, so the ABS should work similar to the other fuel vehicles, the failure may be due to the design of elecyronic control unit(ECU)
    I am a design engineer in Mechanical field

  • Haneesh

    sorry that is electronic


  • Jonathan Mathews

    I had this problem twice, the last time it caused an accident. Toyota denied any problem and took no responsibility.