Warning: My 2010 Prius brakes failed while driving!

I hear the high pitch whining sound when you stepped on the pedal the first time in my 2013, which raised some concerns. Members here and dealer techs say its normal regen brake sounds, so I didn't pay any mind to it even though I do find it unacceptable. That squeaky noise when you stepped on it is a second time I've never experienced. Hope they fix it for you.

 

Yap, the squeaky noise was abnormal alright. I'm glad you are fine. Not sure how you stopped by "pumping the gas pedal." Did the emergency brake work?

Have you reported this to NHTSA? File a Vehicle Safety Complaint Form | Safercar.gov | NHTSA

Now, what's with the vote above. No option for NO?

 

Let us know what the dealer says.

I'm not a mechanic but I recall a similar experience with a poster was a master cylinder. A big hit financially if not under warranty.

 

So you have not had the car checked out to see what component failed or was damaged yet you automatically assume it is a recallable safety problem? There is absolutely no chance that road debris could have damaged something dangling under the car?

I'm all for reporting the issue if it is indeed a major fault by Toyota but maybe we should wait for a proper diagnosis.

 

How much pedal force did you apply to the brake? Did you use your full body weight, or at least 112 pounds (metric 500 newtons)?

I ask because that pedal force is a magic number in federal passenger car brake regulations regarding power assist failures.

 

Why do you doubt the emergency brake would have worked? You realize it's a completely redundant system, designed specifically for this purpose.

 

I never heard the brake accumulator (that whirring sound you hear when you first open the drivers side door). I wonder if that is inoperable.

 

Have you ever used old fashioned no-power-assist brakes? If so, did you push as hard in this case as some of the old unpowered brakes on heavy cars and pickups required?

I ask because the federal brake regulations allow power assist failure modes that revert to old fashioned non-power mode, where your foot provides the entire power for braking. In this mode, pumping is not necessary, just keep the pedal down with all the force you can muster. Failure to stop the car in a certain (long) distance from a certain (highway) speed with a certain brake pedal force (112 pounds) is prima facie evidence of flunking this regulation, and should be reported to the link in post #3 above.

If you applied less than 112 pounds, then the issue of brake system problem vs operator error (or both simultaneously) becomes much fuzzier. There could still be a hidden system problem that should be be remedied, but the legal leverage to find it is not as strong.

Please follow up on this issue. This forum has seen multiple hints of a problem of this sort, but reports are still too scare to form a critical mass and discover what is really happening.

 

The last choice is a truthful answer for anyone who has read the OPs comments, so no need for a "no" option!

 

If the pedal actually went to the floor the force exerted is a moot point. In the case of a conventional, vacuum booster the pedal travel actually decreases and the pedal feels "hard". This sounds more like what would be the main symptom of a hydraulic line failure or master cylinder internal seal failure.

 

You are absolutely never supposed to pump the brakes if you need to stop in an emergency.
Just press the brakes as hard as you need to one time. Every time you release the brake so you can "pump" it, you are just increasing the likelihood that the brakes are going to completely fail.
This brake-pumping habit is what causes runaway cars where the drivers claimed the brakes stopped working and are not lying.

 

This is not a conventional vacuum booster system. From first-hand experience in my first Prius, I know there can be some sort of fault where the pedal falls a long way towards the floor and feels like no brake. But it did not involve a line or seal failure, because it reset back to normal after rebooting the car. Both my incidents happened in a parking lot, from a standing start on a gentle slope, and I rebooted before thinking, before trying to put all my weight into the pedal.

The brake pedal could fall most of the way to the floor, but not all the way, and still pass federal requirements by responding appropriately to full body weight. But the pedal feel could be so different from what drivers are accustomed to that they don't react correctly.

A few other drivers have reported similar events. One reported crashing with property damage, and couldn't say how much pressure he applied. Another did apply full force, and the car did stop quickly enough for old-fashioned unpowered brakes. While such a problem, if it really exists (as opposed to some yet-unidentified driver error), should be fixed. But first it must be identified, and if it really passes existing regulations then the legal urgency isn't as high.

It depends on the emergency. That sounds right for some true brake problems, or for a true sudden unintended acceleration (SUA).

But for the most common cause of SUA -- pedal misapplication -- pumping provides a quick clue to the driver about what is wrong. (I speak from first hand experience is a past car.) It also works in bad traction conditions (snow, ice) with (now old) non-ABS cars, and ought to be in a driver's toolbox in case of ABS system failure.

 

The video above shows the brake system failing directly because of pumping the brake against the car trying to accelerate. It was obviously dramatized and I would hope it would not fail as quickly as it did in the video, but it explains these stories of people who said their gas pedal was stuck wide open AND their brakes happened to fail at the exact same time. Either the power brake system fails as shown in the video or they burn out or glaze over the brake pads by pressing an releasing which allows the car to speed up and become even more difficult to stop when they let off the brake.

 

9 posts? I smell a troll.

 

Is your name Spock?

As a typical illogical human, I failed to see it that way. Thanks for explaining.