Warning: My 2010 Prius brakes failed while driving!

You are not helpful, we are talking about master cylinder failure here.

 

Not recently. I checked it for UIA concerns last year.

I agree that if the master cylinder failure is becoming common then this is a very serious issue and I don't mean to belittle it in any way. I just want to make sure we are not confusing this issue with others.

 

Most of those failures were reported in 2010 IIRC. Was the part redesigned in 2011? If so, 2010 should be recalled. Does anyone know?

I did some search. I hope I understood correctly.

The 2010 part# is 4705047140

BRAKE BOOSTER ASSY, W/MASTER CYLINDER. BRAKE MASTER CYLINDER (PRIUS (ZVW30)). # 4705047140, 4705047060


The 2011-12 part# is 4705047180

BRAKE BOOSTER ASSY, W/MASTER CYLINDER. BRAKE MASTER CYLINDER (PRIUS (ZVW30)). # 4705047180


There was also part# 4705047060
but not available anymore (defective???)

BRAKE BOOSTER ASSY, W/MASTER CYLINDER. 2012 TOYOTA Prius # 4705047060

 

That's pretty much the case on every car.

 

I think you would be shocked at how many people probably don't know that you aren't supposed to pump your brakes when you have ABS.

 

But doing so won't cause brake failure. It takes away much of the benefit of ABS, but still works as well as pumping old fashioned non-ABS brakes. OP's description clearly indicated that something else was happening.

 

True. But I owned many cars in the last several decades and have been active in many automotive forums for more than a decade and never heard of total and sudden failure of brake master cylinder until this. While this is still a rare event in 2010 prius, the pattern does emerge though. I guess the high tech design makes it more vulnerable to failures. Based on that, I made some trial stops using emergency brake just in case I need to use it once. It's weak, but it works and stops the car at low speeds. Not sure about high speeds. I personally prefer a hand brake as it can be moderated easier.

 

I'm somewhat relieved I'm not the only one with this issue, but on the other hand I still have the issue. I have a 2010 Prius V (5) with about 70k miles. I had the EXACT same issue with loss of power and the dreaded squeak. I brought it in to A1 (New Haven CT) . They replaced a brake position sensor (i think)...still squeaked...then the whole master cylinder...still squeaks...I'm headed down there this afternoon to bring it in again. Thankfully my insurance company has been working with them (mechanical breakdown), but this is a major issue if multiple Prius are having this.

 

File a Vehicle Safety Complaint Form @ Safercar.gov (NHTSA)

Go one step further and write to PETITION the NHTSA to open a DEFECTS INVESTIGATION into the matter. This agency must respond to you in a timely manner once it gets your facts.

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Here it is.

Recall For Some 2010 Toyota Prius, Lexus HS 250h Models

 

I still don't understand the OP saying this: "and was able to slowly get the car to stop by pumping the gas pedal."
Say what?????

And then he goes on to say he didn't think using the emergency brake would have worked.

It amazes me how many people don't understand and have never been told and trained about using the Emergency Brake as an Emergency Brake. It is also called the Park Brake, but that is a secondary function.

I blame a lack of proper Driver Training. If your Dad doesn't know, how can you get the training.
How are new drivers trained these days?

The Emergency Brake is a mechanical cable system. It will work No Matter What. Total car system blackout, EMP in the area, Zombie Apocalypse....
You step on that pedal and you will slow down. Try it. Practice for when your brakes fail.
That's why it's required in all cars.

F8L, Thanks for the recall info!!! I got myself registered.

 

Unless it's a 2003 Ford Focus. I used the parking/E brake when parking on a hill and the cable snapped.

 

I've got a 2013 car that is 6-weeks old and the brake pedal slowly dropped to the floor at a traffic light today (with my foot applying gentle pressure.) I'm going to take a look for any errant brake fluid. At first blush it has all the earmarks of a failing accumulator/booster or a fluid leak.

Anyone had this happen on a brand new vehicle, basically right out of the box, or am I just looking at normal behavior for the braking system on this thing?

Thanks.

 

Dang Eliot,
I would drive carefully straight to the dealer and get a ride home. No where else.

You do know the Park/Emergency Brake pedal is your last ditch mechanical brake system, correct?

Please practice with that pedal.
It sounds like you are driving a very dangerous car.

Good Luck

 

In fact, I just got under the car in our parking lot at work and see a puddle of brake fluid, so I'm headed to the dealer now. Yep, i am exceptionally familiar with the emergency brake and ABS brakes.

 

Please keep us updated on what failed.

Mike

 

A little more detail about the video. The vehicle is a Toyota Venza with a conventional vacuum brake assist. If the engine is operating wide-open-throttle (WOT), then there is very little engine vacuum available and if you pump the brakes you will deplete the vacuum in the booster reservoir (goes to atmospheric pressure) and you will lose assist. But if you have a brake fluid leak, pumping the pedal will re-supply brake fluid to the brake lines and you will be able to restore braking -- until you deplete the fluid reservoir.
But nothing in the video applies to the Prius -- if you engine is operating WOT, you'll still have the electric boost pump. Actually, the engine shut off does apply to the Prius.

 

I don't think it's wise to drive the car in this condition. Please let us know that you're OK.