Toyota Prius Brake Problems



  • bwilson4webbwilson4web Member Posts: 80

    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 Member 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 Member 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.
  • bwilson4webbwilson4web Member Posts: 80
    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 Member 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?
  • masterpandamasterpanda Member Posts: 19
    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.
  • masterpandamasterpanda Member Posts: 19
    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.
  • silver9276silver9276 Member Posts: 2
    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 Member Posts: 138
    So why are you still driving it?
  • wwestwwest Member 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.
  • cgollihercgolliher Member Posts: 16
    edited March 2010
    Last night I was out driving on a rural road, came to a hair pin cure, one I have driven through hundreds of times, couldn't seem to slow down enough to make the curve and went straight into the grass embankment. Car is not at the auto body shop with I am sure at least $5,000 or more damage to the front end. I have only had the car for three weeks. After it was all over, I just could not understand what or how this happened. After having some time to replay everything in my mind, I believe it is the prius brake issue. Country road, potholes, and some gravel on the road. Wow, my honda accord never had a problem with this cure which I travel almost daily. I am very concerned and upset. I was only going about 30-35 mph when I began breaking. Any one else exp this type of problem?
  • 07prius07prius Member Posts: 10
    I believe that I have (see earlier posts) but I do not have enough hard data to know for sure, ie: I do not know the exact distance I was away from the car I rear-ended, although my habit is to travel at least 100 feet behind cars in front of me, as I know that tail-gaiting is unsafe. I, too, was only travelling 35-40 mph, if that, as I remember I had just come around a turn at about 25 mph (the speed limit for that turn, even though most people were driving faster than that). I often use cruise control to improve my gas mileage and prevent myself from speeding, and I was just getting up to speed as the speed limit after the turn was something like 40 mph. Anyways, like I said, the are too many subjective factors in my case. I have a 2007 Prius.
  • 07prius07prius Member Posts: 10
    P.S.: For me, I think the problem is more to do with the TRAC system than the brakes. I took my Prius to the dealer and reported this to them, however, go the same line as everyone else: "The car's operating as it was designed to." TRAC cuts power to the engine and brakes when the computer senses that there's even a slight loss of traction, which naturally happens when panic braking, and this is not what needs to happen when in a situation where panic breaking is necessary. Yes, I know we're all better drivers than everyone else, but sometimes there are situations where panic breaking is necessary no matter how safe of a driver you are.
  • margiepriusmargieprius Member Posts: 7
    I had my 2010 Brake Fix about 3 weeks ago.(after reporting the problem to the dealer and being told there is nothing wrong 4 times) The problem of slowing down, hitting a bumb and the temporary loss of brakes is gone. What the fix has now created is another problem that I have now experienced 3 times since the "fix"- when I am slowing down the car and hit a pot hole or bumb while turinng the car lunges forward. It is not something that I can not control, but the car litterally rattles and moves forward. I have contacted toyoto corporate and have an appointment with service for Friday- I can pretty much guarantee they will tell me as they have in the past there is nothing wrong with the brakes- my experience with my Prius has changed my opinion of Toyota, and I truly believe the Prius is over "electronic" and they simply do not know how to fix it- My original intention with the 2010 was to allow my 16 year old twins to drive this car when they are able to drive. I would never permit a new driver to use this car- the braking is still a major issue and Toyota after the recall has failed to address the "new" problem..shame on Toyota
    I have every intention of seeing this through, I did not buy a new car only to have to alter my driving, while Toyota denies their Gremlins...I intend to utlilize my rights under the Lemon Law in my state and through arbritation..the question is, when they refund my money what "car" shall I buy? S
  • cgollihercgolliher Member Posts: 16
    I also purchased my new prius with all intentions of allowing my 15 year old drive this car as he learns to dirve. NO WAY will I allow him behind the wheel of this Pruis!!!!! It could be his coffin!!!!!!!!!!!!! If your car is lunging forward after exp uneven roadway, that is what mine did after the brakes failed. I do not believe that Toyota totally understands how to completely fix all their problems. I DO NOT TRUST TOYOTA at this time !In response to your question as to what to purchase next, check out the Ford Fusion hybrid. It is a nice car with good gas mileage and no reported problems as of this date. As for me, after my collision, and the "NO RESPONSE" I am getting from Toyota, I am going back to a car made by an American car company. I had 3 Ford Explorers during their recalls. Ford was prompt and I felt taken care of, and most of all safe.
  • hal_cathal_cat Member Posts: 11
    The media and many posts on this board comment on how the problem with the Prius and other Toyota cars could be electronic. I think we need to be more accurate. I don't believe the electronics (circuitry) is the problem, and when Toyota says the electronics isn't the problem, I tend to believe them.

    My strong belief (based on years of designing software for engine and transmission controllers) is that the SOFTWARE is the problem. Either in the ABS or the Engine controller, or quite possibly the communications between them. The low incident rate for failure is a primary indicator to me tha the problem is software rather than hardware - hydraulic or electronic - since the physical problems would tend to persist continually rather than rarely.

    Note that the 2010 Prius recall involves "flashing" the ECM (reprogramming the Engine Control Module).
  • whitey9whitey9 Member Posts: 138
    edited March 2010
    Did anyone see the report that was featured all day long on all the news channels yesterday ( Tuesday, 09 March 2010 ). It featured an older man and his '08 blue Prius ( license # FRUGL 08 ). He was reported to have reached speeds of 94mph and was "rescued" by a state trooper.
    The ordeal lasted some 30mi as he swerved in/out of traffic to avoid collisions.
    The thing that surprised me was the fact that the man was afraid to place the transmission in "neutral", since he did not "have a lot of experience with these transmissions", and that he was afraid the car would "flip" if he shifted into neutral. I don't understand.
  • wwestwwest Member Posts: 10,706
    Maybe the driver knew more about the Prius, or any HSD, CVT, PSD, Power Split Device, than the average driver. These HSD systems do NOT have a TRADITIONAL neutral gear "position". The ICE and the two electric motors/generators are ALWAYS mechanically coupled to the drive wheels.

    IMMHO it is entirely possible that the driver tried shifting into neutral earlier but with no effect. Remember that if this is a cruise control problem the CC disables itself below about 35MPH. As is apparently what happened with Ms Smith's incident.

    If the brakes did not work to put the HSD system into regen mode then something OTHER than a stuck gas pedal was amiss. The CHP officer stated that he saw the brakes lights going on and off so we know the brake light switch was working. Even if the driver was at fault and for some reason kept the gas pedal fully depressed the brake application should ALWAYS result in the HSD system switching into regen mode.

    That latter effect is exactly why Toyota/etc has been saying the HSD vehicles already have a BTO, Brake/Throttle Override. Apparently they do not.

    Had that incident happened to me I might have tried "shifting" into neutral but would have (hopefully) been prepared to quickly shift out of neutral in case the result was totally LOCKED front wheels.
  • chucko3chucko3 Member Posts: 793
    edited March 2010

    Not necessary. With a low rate failure like that I would think it's a hardware issue.
    The software is the same for every model. So if it's the software issue, the problem should occur in every car same model. Unlike hardware, software does not break down over time. There are so many things which can cause hardware intermittent glitches: power surge, temperature, bad components, loose soldering, etc.

    If the hardware glitch or the problem can be fixed or prevented by the software, the fix will be done by the software because it's easy to replace and cheaper. Been there done that.
  • masterpandamasterpanda Member Posts: 19
    To shift to N or not shift to N is argued both ways by a variety of different people, some of them apparent experts on this forum, and I remain confused. BTW, I drive my 2010 confidently and am not really worried about UA, but the constant din of hyper-amplified reports and complaints make me want to be prepared.

    Even at a standing stop, the shifter/joystick seems almost completely fluid, and getting it to stay in neutral takes a tiny bit of concentration, as there is no reassuring click, the way a mechanical shift would work. Reverse and drive are easier because they are at the ends of the pattern and thunk lightly into place.

    I have tried shifting to N at low speed, and have some concern about inadvertently putting it into reverse while I am moving.

    I am really concerned about the possibility that at, say, 50 or 60mph, the wheels might lock, as you suggest in your comments.

    What is, or where can I get, the definitive advice on shifting to N? Do it/not do it at what speed(s)?

    This is one area where Toyota is truly irresponsible, as it does not deal with this issue in a straightforward way, nor the companion issue of whether or not to try to kill the engine with the power button.

    I have talked with my dealer, read the Toyota web site, read a tech manual that dealers use, read Toyota pronouncements in the media, and the advice is still not fully clear or consistent. (And, amazingly, neither is the presence or absence of real or functionally equivalent BTO on specific cars. It iis as if the Toyota PR experts are singlehandedly creating a reason to commit seppaku.)

    Toyota is hedging simple solutions for some reason, perhaps because it still wants to attribute all problems to Toyota's maldesign of the floor mat (in my view a ridiculous red herring in any Prius), sticky pedals (on cars other than Prius) or driver error. My personal guess is that most UA incidents are actually due to driver error. But, in a disconcerting pattern, Toyota has not convincingly shut the door on the possibility of a software glitch or some induced RF interference with the ECM.

    I did not think it possible a month ago, but Toyota is well down the road to killing its brand. Half the problem is the idiotic media, self-serving experts, and clowns in Congress and DOT. However, Toyota is proving to be an incompetent crisis manager and awful handler of customers.
  • hal_cathal_cat Member Posts: 11
    I hadn't thought about the problem of shifting into N until I read your message, then realized that I had encountered the problem - in the car wash. Twice now I have taken my 2010 Prius through the wash, and of course they want you to shift into N. Both times it took several tries to hit N without going into D or R. The lack of any tactile feedback absolutely compounds the problem, or perhaps not having a channel to the left to unambiguously move the lever into. I am sure that in an emergency it would be almost impossible to hit N if it is that difficult in a car wash.
  • cgollihercgolliher Member Posts: 16
    Dear hal_cat,
    Be very careful on roads that are uneven and rural. Getting into a collision and not having the feeling that you can control your car is frightening!!! I for one am glad the media is running with this, if not it would go unheard. My insurance company, State Farm is the very company who brought the Prius problem to Toyota. I have attempted for days to get in touch with Toyota, the will not even answer their customer complaint lines, the dealer keeps telling me I need to deal with Toyota directly, Toyota sends me emails telling me to deal with the dealership. I have a 4 week old Prius with $6,000.00 worth of front end damage! It is at the auto body shop as I write this note. I have NEVER been in an auto accident before in my lifetime of driving. I am a safe, cautious driver. I will never drive this car again!!! Good luck with yours. Be very, very careful especially if you are transporting precious cargo such as children!!!
  • margiepriusmargieprius Member Posts: 7
    I live in the northeast, and after a harsh winter our roads are in bad shape. Worse than the roads, is the prius ability to handle bumpy surface. Just driving to work my 2010 Toyota Prius, jarred forward over 3 potholes. The handling of the car on these road surfaces is horrible, and the behavior of slowing down and turning on a bumpy surface is totally unacceptable...I have had the "FIX"- on my way tomorrow to be told there is nothing wrong with the car-then on my way to the Attorney General- Using my states Lemon Law to return my Prius..If they will not admit there is a problem how can they fix it. This will be my 6th time in for what they term "brake inspection"- prior to the fix I reported "brake Failure" it was written as "brake inspection" Car lurching forward over potholes- lets see, check wheel alignment..I have 4 toyota's- soon I will have 4 of something else..
  • wwestwwest Member Posts: 10,706
    "...The problem should occur in every car same model..."

    Every car may be subject to the problem but it could be that UA depends on a certain unique/rare sequence of events. Simultaneous, within a microsecond, brake application and CC "set/accel", say.
  • whitey9whitey9 Member Posts: 138
    edited March 2010
    As I sit here inside my home, I think I remember that Neutral on my '07 Prius is at the 9 o'clock position. Straight across to the left from the normal driving position. ( I have 6 cars, 3 of them are Toyotas. ) All I would do is move and hold the shifter there until I heard the engine rev to MAX RPM. Today's engines are protected by an overrev limiter, so no worries.We have been driving toyotas since '86, and know that while they have all been good cars, none of them have been great cars. They do most everything well, but in no aspect do they represent the elite of automobile developement. They just are good cars for doing what cars are supposed to do - getting you from here to there, and back again. I worry more about being rear-ended or head on, or by an uninsured driver than my Prius running away. I believe Toyota should do what M_B did several years ago. They made it impossible to accelerate when the brake pedal is depressed. The brakes have priority over the accelerator by the signals sent from the switches built into the pedals. NO MORE POWER BRAKING!!!
  • wwestwwest Member Posts: 10,706
    edited March 2010
    With a Toyota HSD vehicle "neutral" isn't neutral unless the SUM of the PSD drive inputs, ICE, MG1 & MG2, add up to ZERO torque at the output shaft.

    If the HSD control system doesn't go into regenerative braking mode, continues to DRIVE the front wheels, with the brake lights on the chances it will response to the shifter's neutral position switch are also doubtful.
  • wwestwwest Member Posts: 10,706
    "..They made it impossible to accelerate when the brake pedal is depressed.."

    The question that arises is how was the BTO implemented..?

    Toyota HSD vehicles already have a BTO in the sense that the HSD controlling microprocessor module is already programmed to enter regenerative braking mode when the brakes are applied. Obviously, absent a firmware failure, that should make it impossible to continue accelerating regardless of gas pedal position if the brake lights are on.

    The only foolproof/failsafe BTO implementation involves using a completely separate BTO module, NOT a simple sub-routine in the master control system's firmware.
  • masterpandamasterpanda Member Posts: 19
    Thanks, but I do not understand what this means. If the car has UA--which I really do not expect more than being struck by lightning--should I try to shift into neutral at 60 mph? 20 mph? or not?

    Also, do you have a view on the advisability of trying to cut the engine by placing the start/power button? Of course, I would depress the brake pedal as hard as possible as the first response.
  • wwestwwest Member Posts: 10,706
    Personally, and having at least some idea of the workings of the PSD, I wouldn't hesitate to move the shifter into the neutral position. But I would be prepared to quickly move it back into drive if the results were adverse.

    I also think it is a serious design mistake to have a dual function start/stop pushbutton. They should be separate and the "stop" PB somehow protected from inadvertent activation.

    And I would not find it at all surprising if the current PB "stop" function is inoperative if the car is in motion and/or the gearbox is still in "drive". What are "our" learned, LONG learned, actions with an ignition key...?

    Anybody out there that turns off the key before shifting into park...?? (or neutral..?)
  • masterpandamasterpanda Member Posts: 19
    wwest--thanks, and hope we get a useful answer to your query.

    Isn't it truly amazing that after all the weeks of controversy, Toyota cannot manage to put out its own, clear, concise, sensible, consistent guidance on exactly what to do regarding UA? There must be a reason.
  • wwestwwest Member Posts: 10,706
    "..There must be a reason.."

    Yes, there is, Toyota/etc is not at the moment "in charge" of their destiny.

    That would be NipponDenso, Denso US. Toyota/etc undoubtedly does not at this time even know the causative factors in these UA incidents. On the other hand NipponDenso might know but be unwilling to say since their market goes far beyond just Toyota/etc.

    That would be a VERY wide "net" if it turns out that NipponDenso is at fault.
  • alex6500alex6500 Member Posts: 1
    I sold cars for over 50 yrs and am very sad to see Toyota have serious problems with
    brake failure on some of their cars.I sold Hondas for 30 +yrs.I would ask that another
    company (in the automotive field) would gladly offer their assistance to help .Yes, i know that deaths have occured.
  • michaelroymichaelroy Member Posts: 4
    Great to hear so many people having an honest discussion about their problems with the 2010 Prius. The PriusChat Web site is full of Toyota apologists and Toyota employees who cry foul and worse any time you discuss the safety issues with the car. Looks like we have more honest and straight forward folks sharing good information.

    I have been practicing shifting into Neutral myself and it is indeed tricky given the nuance of changing gears without going too far and putting the car in reverse. Ridiculous that they made it so hard to switch into Neutral - as bad as it is that they put the "EV/ECO/POWER" buttons far away to the point you have to take your eyes off the road to change modes.

    Regarding the braking issue, like many others discussing this issue, I have been fighting this battle with Toyota for 7 months and got nothing but dismissive responses that the car is "operating as designed." I got the "re-flash" recall repair last week, but sure enough, I experienced the same loss of braking power this evening and will continue this battle with Toyota until they fix the problem, I win a lemon law suit, or they buy the damn car back. :lemon:
  • margiepriusmargieprius Member Posts: 7
    My 2010 Prius and I are looking for other car owners who say thats enough lying-

    I went into my local toyoto service , My complaint:
    "When going over bump and slowing down, depressing brake the car seems to lurch forward"
    When I was out with the "toyota hybrid expert" he recreated the braking issue withink two minutes of driving the vechile and told me this is normal for this car and that every other Prius on the road does the same thing- yes it does feel like the car is lurching forward, but if I watch the odometer the car is indeed slowing down.
    His written response difers from his verbal response, as he is getting paid by toyoto not by me

    "Antionio Romano test drive vehicle with customer and going over bumpy road and turning vehicle when depressing brake pedal vehicle VCS activates and stops vehicle. Vehicle does not feel likes its lurching foward and vehicle does slow down to a stop. This is a normal characteristic of the VSC system and vehicle is operating as designed. Like other 2010 Prius's perform in the same manner"

    While Mr. Romano wrote this on the paper he explained in the car that this was a result of the "fix"- he also told me if I attempt to bring in my Car under New Yorks Lemon law he will bring in 10 Prius's that all operate the same way, and I will loose. 2010 Prius owners I need your help. I have had cars before with traction control, VSC, and this is not how a car should feel over a bumpy surface- this is not what I bargained for when I invested in a car for my family- Can I gather TEN 2010 Prius owners who will stand up against toyota. I would advise anyone in the tri state NY/NJ and CT area to record your conversation when you are out on a road test with your "expert"- what they say to appease you and what he puts on paper are two very different things.
    Where does that lead a Prius Owner?
    please contact me, I would be willing to organize and attempt to do battle with the likes of Toyota.
  • michaelroymichaelroy Member Posts: 4
    The fact that other 2010 Prius also momentarily lose braking power actually SUPPORTS your claim that there is systematic problem with the cars that Toyota can't fix - you should actually include that Toyota techs quote that other Prius' act in the same manner to support your lemon law claim.

    In regards to what the dealership puts on your record, you can insist that they put down YOUR COMMENTS as you would like them to read on your record - that's what I have insisted to do. If they protest, just ask to see the Manager and they'll let you get what you want on the record. The fact that the Prius brake "fix" is not fixing the problem will come out soon enough and Toyota will continue to have their hands full of angry Prius owners. Right now your best bet for getting full refund on your car is the lemon law - a class action or civil suit will likely take a long time and may not get you the full value back.
  • ks2010priusks2010prius Member Posts: 5
    edited March 2010
    I purchased a 2010 Prius IV in June 2009. I had no complaints until the weather got cold. I live in Kansas and between Nov and March of each year it is below freezing most of the time. Then in Nov 09 I noticed the brakes would give out just for a fraction of a second when coming to a 'soft' stop, like at a stop sign. It happened once every few weeks, particularly when I left my office. Just as I leave my office there is a street with a 20 mph zone and it is a slight decline to a stop sign. At the same place the brakes would fail for only a foot or two. This seemed to happen more when the car was cold. Then I noticed it would happen sometimes when I was braking over a pothole, manhole or rill in the road, like when the asphalt pavement buckles over time. When it happened several times again at the same place, about 20 ft. in front of the stop sign, I noticed the road was buckled upward at that part of the road. It was at this exact place the brakes would fail whenever I tried to repeat the problem. It was not a major concern because the brakes would always reengage quickly, but I was concerned that at sometime in the future they may fail completely. I reported this on the NHTSA web site before Toyota admitted there was a problem.

    I checked my VIN and it was on the recall list so I took the car in for the brake repair, which amounted to a software update. That was about two weeks ago. The brakes functioned correctly until this last Thursday when I came to a gradual stop on the same street leaving my office. The same thing happened. I lost all braking for about a foot or two until the ABS kicked in. I have a 1989 BMW and the ABS brakes on it always function flawlessly. The ABS sensor receives signals from the front brakes and makes adjustments at a rate of six times a second. Like a fast stutter. You never get a feeling the brakes are not functioning correctly. The 2010 Prius ABS system, on the other hand, appears to be only sensing braking forces at a rate of about a half second, which is way too long of an interval. Whatever technical issue is responsible for the lack of braking control, it needs to be fixed. I am a safe driver, leaving plenty of distance between my car and any objects in front of me. But I'm always concerned the brakes may get worse.
  • wwestwwest Member Posts: 10,706
    First, keep in mind that your Prius is FWD, as are most of these new hybrid vehicles. But that means the regenerative braking occurs ONLY on the front wheels...!!

    So if there is even the slightest indication(***) of the need for ABS activation the system MUST be INSTANTLY switched OUT of regenerative mode. And keep in mind that once frictional brakes are brought "on line" the braking effort is now distributed front and REAR. That alone may be sufficient to alleviate the need for continuing ABS activation.

    That brief "lurch forward" is the result of the need to INSTANTLY disable regen braking and then exetend the caliper piston in order to bring the brake pads into firm contact with the rotor.


    *** The "gain", quickness of activation, of the anti-lock braking system may well be increased as the OAT declines to near freezing and below.
  • masterpandamasterpanda Member Posts: 19
    Am not surprised or skeptical about your account. In my case (w a 2010, IV bought in December), I noticed the problem and got used to it. The "surge" forward after a bump is something I automatically respond to.

    My only question is: do you think in those couple of feet where you sense loss of 100% of braking action, the brakes might possibly have worked if you had pushed the pedal more than usual?

    With my limied knowledge, I can't easily see a 100% failure, except, sometimes for some reason, at the point when regen braking ends and friction braking begins--about 18-20mph..
  • wwestwwest Member Posts: 10,706
    BMW or MB, I don't remember which, are now using a technique wherein the brake calipers are given a light brake fluid pressure "pre-charge" if the automatic windshield wipers detect rain. The idea being to continuously "wipe" the rotors with the brake pads to keep them dry(er).

    I don't know if the HSD system does something like this or not. But if not I could easily imagine a ~200 millisecond gap in braking when regen braking is disabled and it takes "time" to bring the brake pads into firm contact with the rotors.

    Personally I think it might be better to delay the disabling of regen braking until the frictional braking can be brought "on Line". That would likely result in a brief feeling of brake grabbing but driver's might be more comfortable with that.
  • whardywhardy Member Posts: 4
    Man at Wheel of 'Out-of-Control' Prius Has Troubled Financial Past,2933,589090,00.html?loomia_ow=t0:s0:a4:g4:r1:c0.0- 00000:b0:z5
    Look, Toyota has been a trusted name in cars for years, I have bought a number of them for my kids as the got the first cars. Our experience was very little trouble. They may have a problem today, but much of this looks like pilling on. I remember what happen to Audi.

    Bill Hardy
  • wwestwwest Member Posts: 10,706
    edited March 2010
    Directly from the factory shop/repair manual for the 2008 Prius.


    (a) Electronically Controlled Brake:

    The skid control ECU recieves signals from the pedal stroke sensor, master cylinder sensor and wheel cylinder pressure sensor. Based on these signals, the skid control ECU calculates the necessary braking force for each wheel. The necessary hydraulic pressure braking force is sent to the hybrid control ECU via CAN communication. The skid control ECU receives a braking force (regenerative braking force) signal from the hybrid control motor via CAN communication. The ECU calculates the necessary hydraulic pressure braking force based on the necessary braking force and regenerative braking force.

    Rephased/structured for clarity:


    (a) Electronically Controlled Brake:

    The skid control ECU recieves signals from the pedal stroke sensor, master cylinder sensor and wheel cylinder pressure sensor.

    Based on these signals, the skid control ECU calculates the necessary (TOTAL) braking force for each wheel.

    The necessary (TOTAL) hydraulic pressure braking force is sent to the hybrid control ECU via CAN communication.

    (In return) The skid control ECU receives a braking force (regenerative braking force) signal from the hybrid control (ECU) motor via CAN communication.

    The (skid control) ECU (re-)calculates the necessary hydraulic pressure braking force based on the necessary braking force and (Less the) regenerative braking force.

    So what happens if the hybrid control ECU is "out to lunch" and never sends the results of its calculation back to the skid control ECU...??

    No braking at all...?? :sick:

    Lean on the brake pedal as hard as you wish but unless the skid control ECU opens the ABS/TC manifolds to allow the master cylinder pressure to reach the wheels....
  • PMOPMO Member Posts: 278
    I am finding through no fault of Toyota ownership most were being told it was new. Then you have the ones that have no idea where to go. There are I would guess a few untrustworthy types as in lottery winners try for a dishonest buck.Then spend time in Jail for the fraud for their deeds.Make sure your kids get them in for any recall NHTSA has a web site for all Toyota recalled cars and has branded them unsafe unless it has been to the dealer for the rework.
  • PMOPMO Member Posts: 278
    My understanding that until 80% has been applied the braking is sending power to Charge the batteries ? This would leave 20% is this time well spent?
  • wwestwwest Member Posts: 10,706
    edited March 2010
    When you apply the brakes then the skid control ECU FIRST calculates the TOTAL braking force required and then sends this information to the HSD control ECU. The HSD control ECU then calculates HOW MUCH (0 to 100%) of this TOTAL braking force can be accomplished using regenerative braking. The HSD control ECU then sends its calculated answer to the back to the skid control ECU. The skid control ECU now RECALCULATES the level of hydraulic braking required minus the level the HSD system ECU "said" it could supply using regenerative braking.

    If the HSD control ECU for some reason cannot supply 100% of the TOTAL required braking force then the skid control ECU will begin supplying its portion, %.

    There are two possible "holes" in this procedure.

    1.) The skid control ECU, CLEARLY, will not begin ANY hydraulic braking absent "knowing" what percentage of overall braking it is responsible for. No "message" returned from the HSD control ECU = NO BRAKING.

    2.) Suppose the HSD system control ECU defaults to 100% when in reality it is currently in WOT runaway mode.

    In case #1 absent some sort of timeout on the part of the skid control ECU there might be no braking, EVER. This, the time out, might actually be the "reflash" currently being applied to 2010 Prius models.
  • masterpandamasterpanda Member Posts: 19
    Have read something like this in the shop manual for 2010, from which my dealer sent me an excerpt. I think I understand the intended workings, but we need your expert opinion, please:

    1. Does the brake system, hardware/software/system control, sound sensible? If not, in what way is it deficient?.

    2. You identify a vulnerability. To your knowledge, has that happened What needs to be done to prevent it from happening?

    3. What would trigger the problem scenario that you describe?

    Thanks as always for your expertise.
  • wwestwwest Member Posts: 10,706
    edited March 2010
    1. NO...!

    Based on the description given in the shop manual.

    "..what way is it deficient.."

    There is a clear need for a timeout. If the skid control ECU does not recieve a "return" message from the HSD system control ECU within a very short period, <100 milliseconds, it should assume FULL braking responsibility and set a fault code accordingly.
  • wwestwwest Member Posts: 10,706
    2. NO.

    "...what needs to be done..."

    See above.
  • wwestwwest Member Posts: 10,706
    3. Most anything. Absent a problem within the HSD system control firmware, race condition, deadly embrace, etc, my best guess would be RFI/EMI.
  • wwestwwest Member Posts: 10,706
    [quote]If all else fails there is direct hydraulic pressure from the brake pedal.[/quote]

    The documentation clearly implies that the skid control ECU will NOT open the ABS/TC manifold ports to allow hydraulic braking to the wheels if the HSD control ECU "says" it will provide 100% of the braking. So it might not matter how hard your depress the brake pedal the resulting hydraulic pressure may not be ported to the wheels or maybe only a portion provided what the HSD control ECU "reports".

    Yes, clearly there should be, SHOULD BE, a "time out" period if the HSD control ECU doesn't report back within a very short time limit, say <10 milliseconds.

    But if you look at the 2010 Prius TSB regarding the fix for delayed hydraulic braking in the event ABS disables regenerative braking then it becomes quite clear that NipponDenso has overlooked, until now, the need for this type of time out.

    It appears, from reading the TSB, that the early HSD control ECU was sometimes LATE (to busy, too many other more important tasks..??) in responding to the skid control ECU's query and the skid control ECU simply stood by and waited.

    Meanwhile......NO braking.
  • whitey9whitey9 Member Posts: 138
    edited March 2010
    Not so much. That SBC braking system on the M-B has been eliminated on all but the most expensive cars. It was a "brake by wire" system with a hydraulic back-up system. All we did after that system was released was to try to make it work properly. There were parts modifications, and software update, after software update, after software update. Finally M-B must have decided it was just too "expensive" to have this system of their most popular cars due to all the warranty claims, so it was eliminated on almost all cars except the SL. It was one of those Formula 1-derived systems that seemed like a good idea at the time, but was just too trouble prone. It had a whole bunch of features such as the rotor-clearing during rain, but could not be adapted to passenger cars without constant updates.
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