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Toyota Prius Brake Problems

366 messages,  Last post on Mar 27, 2013 at 6:44 AM

You are in the Toyota Prius Maintenance & Repair Forum.

What is this discussion about? Toyota Prius, Brakes, Hatchback, Sedan

    
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Messages Page 37 of 38

#355 of 366 Re: 2010 Prius unintended acceleration accident [ks2010prius] by lily2012

Aug 07, 2012 (6:17 pm)

Replying to: ks2010prius (Aug 06, 2012 4:07 pm)
I was trying to stop the prius when i saw a car coming on my way. My foot was on brake. But the car itself suddenly accelrated, and turning >360 degree backward in a few seconds. I can't control the car when the car was going crazy like this. I was very scared that I passed out. I am a female, never had experienced such a terrible situation.
 
I found a website describing the unintended accelration in two situations: low speed and high speed. "low speed" refers to when we are parking or or backing up or trying to change a parking position when the car accelerates by itself; "high speed" means when we are driving it froward in relatively high speed. My case is the "low speed" one.
 
I contacted Toyota. They will take the EDR (Event Data Recorder) to analyse--it will tak up to 3 months for them to do it! But I am afraid they will conclude that I stepped on both Brake and Gas paddle at the same time, like some posters said.
 
I was pround of my Prius before the accident. I told a lot of coworkers how fuel efficient it iwas. Some of them brought Prius recently, some of them were planning to buy. But now I am much more concerned of safety than saving gas. When they heard of this accident (some of them saw it), a lot of them don't want to go with Prius.

#356 of 366 Re: 2004-2009 Prius Brake Failure Rate is High [jpeters1970] by markgreen

Oct 01, 2012 (11:31 am)

Replying to: jpeters1970 (Jun 27, 2009 9:06 pm)
Apparently those "extraordinary set of circumstances" happened to a large enough number of people that the manufacturer decided that a fix was needed.
 
http://www.edmunds.com/car-news/toyota-prius-recall.html
 
From the article:
A Toyota spokesman said the Prius braking problem is caused by a computer glitch which creates a lag in response between the regenerative braking system (which captures energy during braking to improve fuel economy) and the antilock brakes (which help the car continue to steer under emergency braking situations). The problem occurs when the brakes are applied while the car is traveling over bumpy surfaces or in wet conditions.

#357 of 366 Re: Prius Brake issue [625k_inc] by bigteej

Oct 01, 2012 (6:29 pm)

Replying to: 625k_inc (Feb 27, 2011 10:38 pm)
I bought a 2011 Prius in March 2012. I thought all the issues with the brakes were taken care of back in 2009 and honestly thought it was all just people trying to get rich. My car has the brake hesitation problem, dealer can find nothing wrong and the dealer said that I was the first person to bring up this complaint. I believed them and thought I had a lemon or that maybe I was just a little jumpy about my brakes. The problem has been happening more and more. I decided to do a little research and I was immediately outraged to learn that this has been an issues with these cars for years and 1000's are reporting it. Dealership doesn't know whats wrong still and that car has developed other electronic issues such as the smart key system malfunctioning and the security system not letting me lock the car. I have a 6 month old car with 10K miles on it and its the first new car I have ever bought but I'm scared to drive it.

#358 of 366 Sudden acceleration, Prius 2011 by glenda7

Oct 14, 2012 (11:45 am)

I have this car for a year now and still experiencing sudden acceleration at times when I slightly press the brakes and the car hits a small bump or pot hole, it accelerates. I almost hit a pedestrian in two incidences, and many times almost rear ended other cars. I complained to my dealer but they said they did not find anything wrong with my car. They have emailed an engineer from California about it. It's been a month and I did not hear from them yet. Does anyone have a solution about this matter? I do not want to get into a car accident or hit a pedestrian....

#359 of 366 Re: Prius Brake issue [bigteej] by wwest

Oct 15, 2012 (10:41 am)

Replying to: bigteej (Oct 01, 2012 6:29 pm)
What you are experiencing is the "delay" in the transition from regenerative, FRONT wheel ONLY, braking, to frictional braking ONLY, braking on all 4 wheels. Not that the addition of rear braking makes much difference in most cases.
 
Obviously the car "wants" to use regen braking, especially so if the HV battery charge is close to being marginal. regen braking only occurs on the front wheels...you know, the one's you constantly rely on for directional control.
 
So any, even the smallest, indication of front wheel slip during braking will be, MUST BE, reacted to instantly. So, would you like to have, with definity, a sudded increase in braking rate, or a "slow" transition into a less pronounced braking mode...?
 
There is a serious level of MG mass inertia to be ovecome inside the PSD/CVT in switching from "brake" to "neutral". The multiphase rotating electric field(s) inside the MGs cannot "lead" the rotor by too great a margin without the possibly of becoming unlocked.
 
And you DO NOT want the frictional braking to come online until most of the regen braking has been abated.
 
Drive the new RWD Infinity to get an idea of the overall driving dynamics of a RWD hybrid vs a FWD.
 
Hard call for the design engineers.
 
An ideal solution overall would be ofr the Prius to become a RWD hybrid.

#360 of 366 Re: Sudden acceleration, Prius 2011 [glenda7] by wwest

Oct 15, 2012 (10:54 am)

Replying to: glenda7 (Oct 14, 2012 11:45 am)
"..sudden acceleration..."
 
More like "lurch forward" as the regen braking is released, "wound down", during the transition to frictional braking, with all wheel "distributed" FRICTIONAL braking and ABS capability.
 
Regen braking can be PERFECTLY "metered", fine resolution modulation, moderation, while frictional braking simply cannot be. So Toyota dare not bring on frictional braking until regen braking is mostly "wound down", the PSD has gone from regen mode (reverse[?]) to "neutral"
 
The only solution I can think of is to ALWAYS brake EARLY and HARD, only lighten the braking once you have slowed to your comfort level with DEFINITY. Always "coast" up to a final stop.

#361 of 366 Re: Prius Brake issue [bigteej] by lyanesse

Oct 16, 2012 (8:11 am)

Replying to: bigteej (Oct 01, 2012 6:29 pm)
I'm having the same problems with my 2011 Prius, purchased in July 2011. After only a month or so of driving it, I started to become scared daily by the unsafe driving conditions due to the car's tendency to lurch forward while braking over bumpy ground coming to a stop. It does not help to always "brake early and hard" as another poster suggested because the car simply fails to brake when it hits potholes - it doesn't matter how hard you're pressing the brakes. I also brought this to the dealer's attention last fall and they said they checked the brake system and there was "nothing wrong, that's just how the braking system works." I know that this exact issue is a problem on 2010's but have not found a recall for 2011's and the dealer claims there is no issue on my car.
 
Well, now this "non-issue" has caused an accident as my husband was driving my car last weekend and the car lurched forward while he was braking over potholes (there are a lot of them around San Diego) coming up to a stoplight and it didn't stop and it resulted in him rear-ending someone. There was no damage to the Prius, just some dings in the bumper of the other car, but $2000 later I feel pretty upset that my Prius clearly is not reliably safe to drive. I'm going back to Toyota soon with my documentation in hand that I brought this issue to their attention months ago and I'd like to see what they have to say now it's led to an accident because they ignored the problem.
 
I also have other electronic issues with it - smart key system not working well either. It completely failed about 2 months after I got it, then Toyota reset it and it hasn't worked as well as new since. Oh and the radio system sounds terrible, with lots of electronic interference that makes the sound very muted. It will sound clear for a split second when I turn the car on or switch from CD to radio, and then it gets muffled. Dealer also found "nothing wrong" on the radio. I do like the car but am seriously frustrated to have spent so much money on a car that does not perform as a new car should or provide the level of safety a consumer would expect.

#362 of 366 Re: Prius Brake issue [lyanesse] by jacquesc

Oct 16, 2012 (9:04 am)

Replying to: lyanesse (Oct 16, 2012 8:11 am)
Keep up the pressure on these problems. I have tried a ton to really fight these issues we are all having. However, on this forum every response seems to be from someone that has been employed by Toyota to pacify the complaints.

#363 of 366 Re: Prius Brake issue [jacquesc] by wwest

Oct 17, 2012 (7:11 am)

Replying to: jacquesc (Oct 16, 2012 9:04 am)
Most defintely not, NEVER, employed by Toyota...
 
Google:
 
"Pioneer 10" Osprey

#364 of 366 When/how do the brakes engage when coming to a stop? by lmmara

Dec 22, 2012 (6:21 am)

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,
Leo

Messages Page 37 of 38

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