Toyota Prius Brake Problems



  • wwestwwest Member Posts: 10,706
    Most defintely not, NEVER, employed by Toyota...


    "Pioneer 10" Osprey
  • lmmaralmmara Member Posts: 6
    edited December 2012
    I have a 2011 Prius III and would like to know when and how it switches from regenerative braking to normal braking when stopping or slowing down? I am also interested in what happens as I apply the brakes when the cruse control is functioning. This knowledge will help us maximize the regeneration and extend our Prius's brake life.

    Thank you,
  • greeninggreening Member Posts: 1
    I purchased a new 2012 Toyota Prius and absolutely loved the car....except....

    Within one month, I had 3 'incidents,' the first was when it transitioned from battery to motor with such severe force, I initially believed I had been struck in the rear.

    The second 2 incidents were BRAKE FAILURE - the pedal traveled to the floor and a dashboard warning light came on - there were NO BRAKES!

    I demonstrated the BRAKE FAILURE to the Route 44 Toyota technician repeatedly as he sat in the passenger seat, yet the dealer's response? "No Computer Error Message" !

    How often has Toyota employed that phony response??

    I refused to drive the vehicle to prevent injury or death to an innocent person, maybe a child in a crosswalk in front of my LEMON Prius.


    The comments and complaints posted here seem consistent with the quirky or failed brakes I experienced.

    Might I recommend that you post your complaints on the NHTSA web site - that's the only way Toyota will correct this problem.

    Consumers also have a right to file a Petition for Defect Investigation with NHTSA in which you itemize other complaints that are publicly available.

    You might also consider posting your complaint on the web site of the Center for Auto Safety.

    How many innocent people must die or be injured before Toyota corrects this problem?

    Whining in this forum doesn't solve the problem.
  • thebrakesthebrakes Member Posts: 1
    I have the same issue as everyone else with our 2010 Toyota Prius...hit a bump and the brakes don't work for a short time AND the care 'accelerates.' I've taken the car to one dealer who says the issue 'can't be duplicated' and the other says that Toyota (corporate) does not see this as an issue so it is not covered under my extended warranty. Has anyone had any luck getting their brakes actually fixed? Any advice? I don't want my wife driving around in a car that is going to randomly accelerate when in fact, she wants to brake.
  • rikki22rikki22 Member Posts: 1
    I've had the same issues with my 2006 Prius. Feels like you have no control for a second when braking over bumps/potholes. One back road I take often has a 90* corner. I never go fast, it is thickly settled with a park and lots of kids. Maybe 10-15 mph over the bumpy patch just before the corner and the problem happens without fail. I usually am able to go around it but not if someone is coming the other way. Some people are saying to apply the brakes harder, that won't work for me as I am not actually stopping, just slowing. It has happened numerous times in other places but this is one place it always happens and as I said, NOT going fast at all. I've read other blogs where many people have had issues with their 2006 as well so how come there was a recall issued only the 2010?
  • typesixtypesix Member Posts: 321
    edited June 2013
    I have had that happen with regular cars with anti-lock brakes when braking on bumpy roads. Cars without anti-lock brakes won't do that.
  • kateinpvkateinpv Member Posts: 1
    I'm trying to understand what just happened in my Prius. It's a 2012 plug in and I have been telling everyone it's the perfect car and it was-- until tonight. I was on my way to a lecture and going down a hill when the car suddenly began to lurch. It's hard to describe it accurately. It was almost as though I had decided to break violently five times in a row. It later reminded me of what happened when our two teenagers had problems learning to drive a stick shift--the car just lurched on it's own. forward and back. The seatbelt went on suddenly as though I were going to crash, throwing me back tightly in my seat. It was very frightening.
    I decided not to go the event. Instead went straight to the Toyota dealer nearby. They were closing but a very kind employee ran and got the manager as he was about to drive home. The manager suggested I bring it in tomorrow morning and they would loan me a car. And he said the problem might be "unassisted braking" something a lot of cars now have.
    I was too scared to continue on to my lecture so I came home. I tried going up and down the same hill since there were no cars around. I wanted to understand what happened. But the car didn't repeat the lurching problem.
    I would greatly appreciate if someone could explain what happened. I'm scared to drive it. But I have really loved the car and had no other problems with it. It seemed like the absolutely perfect car. Would appreciate any input or solutions. Tomorrow I will take it back to the dealer but in reading the other posts, I suspect that there isn't a problem that will be detectable. Although I don't know that yet.
    Thanks in advance for any and all input.
  • aslwinaslwin Member Posts: 1
    I have a 2007 Prius. The car was involved with an accident on August 30, 2013 because "no brake". It was in a stop and go situation travelling at about 20 miles per hour. The car in front stopped, I slamped on the brake and TOTAL no brake. My 16 years old son sitting at the car observed the "no brake" scenerio. There was a 25 pound of rice at the truck did not even more. No skip mark... nothing. Took my car to Longo Toyota and found nothing with the brake system other than the front pad is thin, tire is marginal etc. None of the findings expain the NO BRAKE scenerio. For some reason I cannot make this NO BRAKE to appear again. I want people to aware of this and gather information to alert someone to review the design of PRIUS braking system.
  • celerybeancelerybean Member Posts: 1

    my break light comes on in my 2013 Toyota Prius

  • PF_FlyerPF_Flyer Member Posts: 9,372

    @celerybean said:
    my break light comes on in my 2013 Toyota Prius

    A few more details will help. Do you mean a light on the dash?

  • llanollano Member Posts: 1

    My 2010 Prius also lurches forward when slowing and encountering a rough surface. It did cause me to bump a pedestrian in a cross walk. I reported it yesterday when I had a recall software update. At first the guy acted like he never heard it before, then when I started to show him on my iPad he admitted I was not the first customer to report this issue. He said I could make an appointment to have it checked which I declined as it appears Toyota has yet to solve the problem.

  • mcgootermcgooter Member Posts: 1

    ;) As an EE (electrical engineer, of the electronics type, with patents on high speed circuits), in the design division of a light rail government outfit, I work alongside the electric motor traction-power team. I have discussed this Prius braking & overall engine-power control with the traction power, software types & electronic types of the EE types. As a Prius owner myself, I have experienced its odd braking behavior. First, I'd recommend Toyota dealer sales persons to stop telling the public the Prius has a "CVT" (continually variable transmission). It has no such thing. My daughters Nissan has one, & the CVTs are turning up in a number of the high MPG small cars. But to my knowledge, no Toyota hybrid on the market has a CVT.

    A Toyota dealer near my home, "claimed" to me, that taxi companies are getting 400K miles on the Prius with no major repairs, including its "transmission". The Prius has no transmission.

    Not having a transmission is both a blessing & a negative. The longer a person has driven regular cars, sticks & automatics both, the more weird a Prius will seem, & the more weird it is to learn to "control" the Prius. Add to this problem, that the "parallel-hybrid" has its inherent complex problems that can be solved, but only with the very best engineering. The Prius is a partially solved parallel hybrid.

    Not having any clutch for a Prius, both removes a maintenance cost, & build cost. But it introduces a very noteworthy problem on “unintended torque to the tires”, as it lacks a true "neutral".

    There are governmental entities actually considering laws to force a mechanical clutch into this type of vehicle. Lacking a clutch, (either manual or auto), then the electronics are left as the only way to keep unintended torque from the tires. If the Prius had its anti-lock/traction-assistance breaking feature turned off, this would help some, but introduce new issues.

    Toyota almost certainly chose the "parallel-hybrid" method, as it delivers the best MPG, for the least engineering cost & lowest manufacturing cost. And lacking a transmission, it can also boast a very low failure rate of its only transmission like device; the "PSD" (power sharing device). A PSD has no slipping parts & no gears or belts to change spin ratios. All regular transmissions, that most of us are so familiar with, have slipping parts, & gears or belts.

    As soon as I, (a hard core engineer type, aka nerd) began to look into the design of the Prius, I find critical components given strange marketing names like PSD (power sharing device). Also Toyota does not voluntarily tell the world how the car works. The best data is published by reverse engineering enthusiasts.

    The PSD is a marketing name for a mechanical “differential”. The Prius also has typical mechanical differential, like all cars to apply power switching to the left or right front wheels. Thus, between the rubber tire contacting the road, & two sources of torque (force that moves the vehicle) are;
    1) the gasoline engine (ICE) & its MG1 (the ICE’s shaft connected electric motor) &
    2) the other MG2 (the bigger of the two electric motors),
    that enter the first differential, that Toyota calls a “PSD”.

    Thus there are TWO mechanical differentials in series, the PSD & the final differential that is closer to the tires. I’m an EE, not an ME, but in my opinion is that two differentials in series, gets a little squirrely, mechanically speaking. That is, mechanical differentials are not perfect, in their function of how humans need them to behave.

    Differentials do have “sticky” behaviors. Generally, most of us drivers barely notice that sticky or squirrely mechanical differential behavior in a regular car or truck. But when two mechanical differentials are in series (like in a Prius), things do get noticeably stickier. “Sticky” regards the inertial behavior of the parts in a differential. The Prius exacerbates the differential’s imperfect behavior, with the motors limitations, & no-clutch, that creats an uncommonly high rotational spinning mass, for such a light vehicle.

    I’d like to see a “ratio of spinning power-train-mass/vehicle-mass” comparison, for a Toyota Corolla & a Prius. And I’d bet the Prius has almost four to eight times the spinning mass, that is directly connected (no clutch, auto or manual type) to the final-differential & tires. The final differential is the last one before the tires.

    Add the two series mechanical differentials, with no clutch to provide a true “neutral” & what Mr. Barr calls “spaghetti code” & overloaded stacks, & yikes, you have a too slow reacting computer, trying to deal with the two-series-differential & no-TRUE-neutral effect, & the list of additional parallel-hybrid issues below.

    The additional issues are limitations of the inductance of the electric motors, that slow down the motors ability to change output, to a torque change request, & the permanent magnets (that improve power efficiency) that spin, that also unfortunately reduce the number of mechanical field positions that can be put in a 360 degree circle, & you have a recipe for jerky mechanical behavior at the tires, as to the needs of the driver in traffic & imperfect road conditions.

    I’ll stick my opinion out into the wind here, & make a guess that there is not a good computer design requirements document for the engine-drive-train-control-computer. At least not a detailed one that states all signals, what the signals must do, & how much time (micro-seconds) that the functions must happen within. Also the engine, the motors & differentials, tires, mass of the vehicle, all need to be mathematically simulated into a complex control system. That’s no small task.

    If engine-drive-train-computer decisions that are being made in 100’s of milliseconds can be made in 1 millisecond or less, that improvement should be pursued.

    For instance, a buddy if mine, another EE nerd, of the FPGA type (field programmable gate array) expert, works for a subcontractor of General Electric, to make FPGA’s that control the jet engines of the biggest planes.

    The jet engines need to achieve the best possible thermal efficiency (lowest fuel consumption for hoarse-power ratio, aka watts), but operate on the edge of compressor-stall, to achieve that goal. The solution is the FPGA, to compute the equations in nano-seconds, that a typical small computer would complete in 100 milliseconds (a tenth of second). FPGA’s use logic parts (like AND & OR gates & flip-flops), that are hard wired, for ultra fast decisions. Whereas the computer of the Prius is a general purpose processor, with a program written for it.

    Back to the Prius, 30 mph, is 44 feet per second. Just 100 ms equals 4.4 per second feet at 30mph. Consider that a computer control output to a motor or breaking device, comes 4.4 feet, after the driver would have wanted that to happen, is not a good thing. Add the unwanted computer control delay to the overly “sticky” behaving components of the drive train, & the result is a lot of jerky, sticky, squirrelly…. (I can’t come up with better lexicon here) behavior that will happen at the tires, as compared to what the driver is expecting.

    None the less, I still like the Prius, as it cut my fuel bill considerably.

  • steverstever Guest Posts: 52,454
    edited April 2014

    Great post, thanks. A recent house guest of ours was complaining about the brakes on his '06 Prius (and six tows for various issues). We test drove a V just this week and crossed it off our list. The problem reports or how it drove weren't really the concern, we just weren't wowed by the space utilization. Not boxy enough (the C-Max gets similar EPA ratings with a boxy design; of course owners have complained that they can't match the EPA ratings).

    I may change my mind about the Prius V after the next generation arrives later this year. And I'd ask you about tin whiskers and SUA, but I get enough flack around here about my conspiracy theories LOL.

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