New GenIII brake recall affects 87,000 cars

This brake override does not work if the failure originates in the engine computer.

 

Sounds like a reasonable exercise to include in a test drive. Let the sales critter know you're going to check the brakes:

• floor the accelerator - just getting a little speed
• slowly apply brake - the override should cause a distinct reduction in engine noise and rpm
• slowly release brake - the engine should resume

Thanks! Excellent addition to a test drive.

Bob Wilson

 

By doing this test, you are only testing the functioning of the BOS for failures it is designed to protect against. AFAIK, without using special equipment, you cannot induce the kind of failures for which the BOS does not work.

 

In a test drive, it verifies the function exists and can be shown to work.

No problem, just describe what "special equipment" or conditions are needed to induce the failure. Let me give a practical example of what I'm asking for using the first Prius brake problem:

• Dec 24, 2009 - first PriusChat posting of NHTSA investigaton.
• Dec 25, 2009 - my first thoughts, hypothesis about what might be going on.
• Jan 13, 2010 - trying to replicate the problem
• Jan 19, 2010 - survey to identify speed range
• Jan 30, 2010 - another survey to identify how to replicate the problem
• Feb 7, 2010 - successful recreation of the problem

Eventually I was able to confirm the fix worked using the tools and methodology developed to replicate this problem. Once I had the software change done to the brake controller, I had no more detectable problems. I still listened to others and tried to get them to replicate the problem but it is not happening.

Now I have always known that one intermittent problem will often mask a second one. We have to eliminate the first before we can begin to work on the second. But the second intermittent problem will have a lower rate than the first. Just I was not seeing reports that suggested there was enough there to debug.

So this thread is about a known problem with 87,000 Prius, brake assemblies. There is a weakness that leads to a fatigue failure in the bellows separating the nitrogen from from brake fluid. We are waiting on the replacement program. So far, no problem.

Now if the "brake override" is a fraud, it should be easily detected in a test drive. But if there is an intermittent problem with the "brake override," we start with a few simple questions:

1. How often?
2. Under what conditions?
3. What are the mitigations?

Does anyone (not just Betsy) have specific incidents where the Prius "brake override" failed? Say date, time, and location?

Does anyone have a description of under what conditions so those with similar Prius can replicate it?

As for use who own earlier model Prius, 2003 and 2010, we still have what was learned from the Saylor crash:

• shift into "N" - no reported failures of this mechanism
• apply brakes HARD - no reported failures of this mechanism
• hold "POWER" button in for a second or so - no reported failures of this mechanism

My mind is open if there are examples of Prius "brake override" failing, especially from the original reporter. But dealing with rumors, second hand accounts, I always advise,"Please contact the original person having the problem and invite them to come here." They are the only ones with direct experience of the problem and we can then investigate what is going on.

Now there may be problems with those still in legal proceeding coming here to chat with us. But if their case has been settled and they are not under a gag order, please invite the Prius owners to come chat with us. Non-Prius owners do not help since their cars have different systems.

Bob Wilson

 

Bob,
I do not know whether the following applies specifically to the Prius, but it was sent to Uchiyamada, who you probably know as the Prius chief engineer, and who is now Toyota's chairman. He was checking his facts before testifying about SUA in the Senate Commerce committee hearing in February 2010 and this is what his subordinate reported to him. Based on other documents I've seen, it is possible that the BOS has been further developed since then and is now gradually acquiring capability of overriding erroneous ECU signals to the throttle.

As for your "special equipment" question, I do not know, but I suggest you contact the Clemson University Vehicle Electronics Lab people and ask them. Clemson Vehicular Electronics Laboratory
*************
To: VP Uchiyamada

Control Systems Development Division​

​

BOS Issue

Yesterday, you contacted us about the unclear “BOS insertion position information.” I’m sorry.
(The source of the information was by word-of-mouth from a Bosch engineer in charge of diesel engines, who lives in Germany. I have asked a person in charge of gasoline [engines] to check.) ）

At the present time, we do not have accurate information on Bosch’s system. We have started work to check this from multiple routes, including the above. I will inform you again by Monday morning, US east coast time.


<Facts that have been confirmed at the present time>
Bosch’s BOS system on board Toyota vehicles such as the Yaris, overrides the accelerator pedal sensor value with a fully closed status when the brake is on.
This standard Bosch module of 02-03 was adopted as it is.
Subsequently, if Bosch has not changed the BOS insertion position, the BOS valid range is the same, but I will check the latest Bosch standard software by Monday morning.

<FYI>
From interview meetings we've had with our vendors to date (Denso, Bosch, Continental, Delphi), we’ve learned that the BOS has an ECU independent of the engine ECU that we discussed the night before you left for the United States on 2/26 (Friday). It appears that at the present time, there is no BOS system that overrides signals transmitted from the engine ECU (including the VSC and cruise control signals) to the throttle drive motor.
Therefore, including other manufacturers, the existing BOS system is located in the engine ECU. I do not think that any one of them can claim to cover all electronic systems failures.

 

Bob,
I am not sure I can agree with that, based on my reading, unless you are specifically talking about BOS as a remedy for brake failure only, and not for all runaway situations.

I do not know whether the following document applies to the Prius or not, but in principle it seems like it would apply. And there are some reports of runaway Prii in which the brakes apparently did not work. For example, Elizabeth James's who landed in the river.

I understand that her problem was not the same as the present recall. It just illustrates that the failsafe failed.

Also, there was a NY Times report on a runaway Prius that was documented by NHTSA. http://www.nytimes.com/2012/01/25/business/lawsuit-seeks-records-from-us-investigation-of-toyota-acceleration.html?pagewanted=all&_r=0

Here's a Toyota internal memo about the gap between the public presentation of the BOS and its actual functioning:

　　　　　　Items of Concern about BOS in the Public Hearing [Congress]

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　Yoshida

Project General Manager Kuzumaki has already been notified about this case.


1．About deployment of BOS in vehicles already sold

Yoshida

　In President Lentz’s answer,
　he said “it will also be adopted in models other than the 7 models announced (*)”, so this was checked with Project General Manager Kuzumaki.
　Project General Manager Kuzumaki spoke with President Inaba and reconfirmed that “the basic stance is the 7 models announced”.

(*) The ES, Camry, Avalon, and IS announced last year and the Tacoma, Venza, and Sequoia added this time
　　　　
(2) About the effect of BOS

　In response to “Are you going to install the BOS at a stage when you have not confirmed the presence or absence of an electronic throttle problem?”, President Lentz answered “it is installed as an extra measure of customer confidence.”

　He answered cleverly and did not say “BOS has an effect on pedal return defects, but if the electronic throttle fails, it has no effect.”

 

Bob and all,
I decided that I've said enough here, and I am not sure it is actually so relevant to the thread topic, so I think I will bid you all farewell and leave off posting.
Betsy

 

I was pretty sure our 2010 Prius did not have the brake override system. Toyota announced it would be in all vehicles by 2011. Still I looked through the New Car Features and found this description of the brake accumulator:


I was able to confirm our particular Prius, delivered May 2009, does not have the brake override system. Fortunately this recall is about the above part.

Bob Wilson

 

You might consider searching all of the forums for "unintended acceleration." There is no problem with resurrecting a relevant thread and that would parallel your interest.

Back in September 2009, after the Saylor crash, there was a lot of interest in unintended acceleration. This is how I knew more than a few of us had conducted experiments to verify "what to do if it happens to you."

Based upon Toyota's press releases, I would expect to find the brake override system in the cars sold after 2011. The first software upgrade in February 2010 did not mention adding this feature. It isn't clear if this feature can be retro-fitted to our early production Prius.

Bob Wilson

 

Now I am unhappy.

I called the dealer last week and confirmed my wife's 2010 Prius is in the recall but they did not have any further information. So I called the Toyota support line, 800-331-4331, this morning and this is what I learned:

• 'We are still looking at a fix but have nothing yet.'
• Q: "Is it dangerous to drive? Should I leave it parked?"
  • A: 'Just continue to operate the car. If (when) the warning lights come on, call your local Toyota dealer for a diagnosis and repair.'
  • Nothing about whether I need to park it right then and there or try to get home or try to reach the dealership.

I'm going to calm myself down and think about what makes sense. My first thought is to contact NHTSA and point out this 'keep driving until it fails' response by Toyota on a brake issue seems uncaring about our safety. Phone advice that we just keep driving until the car fails, well this sure sounds like 'land shark' bait to me.

At a minimum, I'm going to establish a 'paper trail' to show I've exercised due diligence. I've contacted Toyota about the problem and its safety ramifications. Once I've done that, I'll follow Toyota's official response 'to keep driving until it fails and then call the local dealer.'

Now I am no fan of our Congress critters but I think there are going to be hearings on NHTSA. Perhaps our critters might like to pass a copy of this communications on to the committees of jurisdiction. Then there is a always a Freedom of Information request to NHTSA.

Here is the text from the Toyota FAQ:

Source: https://techinfo.toyota.com/techInfoPortal/staticcontent/en/techinfo/html/prelogin/docs/cp/d1htofaq.pdf

Bob Wilson

 

The reason for the recall hasn't resulted in any sudden and drastic loss of the brakes from reports. Spongy brakes aren't going to prevent the brakes from stopping the car when it is first noticed. So a 'drive until failure' seems to be a reasonable response from Toyota. Perhaps the warning light is coming on before any noticable brake degradation is noticed by the driver in most cases.

 

First I wanted to read some reports. Others have reported total brake failure but it wasn't clear if their loss of braking was associated with this specific problem. However, I was able to find some info on the NHTSA web site.

There are five attached documents and the first is Toyota's letter with this paragraph:

Source: http://www-odi.nhtsa.dot.gov/acms/cs/jaxrs/download/doc/UCM439361/RCAK-13V235-8848.PDF

But the real find is Toyota's description and analysis of the problem:
http://www-odi.nhtsa.dot.gov/acms/cs/jaxrs/download/doc/UCM439269/RCDNN-13V235-2333.pdf




This is the type of information and detail I need to have a handle on the failure mechanism. Yes, it will be somewhat gradual and not a sudden loss of braking force. I would go home and on the next business day, drive the car carefully to the dealer.

Bob Wilson

 

I think that it is relevant to note that the above description is based on the events that led them to this recall. It started with the driver getting a warning light and bringing the car in for service. It didn't start with an analysis of a crash. One could argue that the warning light system is working as designed...and warning the driver of a problem that needs to get fixed. Replacing the (insufficiently robust) bellows with another identical one is a viable solution -- but even better to have one that won't go bad.

I'm not worried about this problem...and my 2010 is in the recall. If my brakes in any car start to feel mushy (warning light or not) I'm going to drive extra careful and bring it to the dealer. If they feel like stopping distance is affected I'll stop and call AAA.

Mike

 

Ah HA! I've figured out how to make the brake accumulator fail!!

I'll fill up the tank and pump up the tires and go for a single-tank, distance drive. About the time the car has say 900 miles and has just started 'flash', Murphy's Law will make the brake accumulator fracture and I can get it fixed.

One good thing about global warming is the improvement in Prius MPG performance.

Bob Wilson

 

Great read, thanks for posting. Do we know if the booster pump is a part of master cylinder that dealerships replaced (for $$$$) when people had these brake problems?

 

? I don't understand

 

The master cylinder and accumulator are separate parts bolted together. The accumulator is the 'power assist' that feeds the master cylinder. The accumulator failure is a mixing of nitrogen gas with brake fluid. Speculation on my part, the failure of bellows might lead to nitrogen bubbles that might lead to disproportionate stress on the master cylinder, piston seals . . . PURE SPECULATION!!!

As I read the NHTSA files, it sounds like Toyota will consider adjustments for those who had earlier brake problems.

Bob Wilson

 

I received the registered letter from the local Toyota yesterday. The expected time for this recall is about 3.5 hours and it will include the check and the potential replacement of brake accumulator. I think that the check will be just a S/N scan and in case of the match they will replace the assy P/N. I don't have the recall's TSB in hands, but I asked for it.

 

I went to my Toyota dealership in Minnesota (Walser Toyota, Bloomington, Minnesota) for a routine oil change for my 2010 Prius V. The service attendant told me that there was a recall on my auto for this problem. "We can't get to it today, but we can get you in Monday." "We need time for the part to be delivered." He couldn't have been any nicer. And, certainly, I was told, we still need to see if your vehicle is one of those covered by the recall. I guess during the production year newer parts were installed. Some 2010 Prius vehicles might not be recalled because of this. After many cups of complimentary coffee and a few hours, everything was complete. I was treated with respect. The new parts were installed and vehicle was road tested. I appreciate my friends that have reported these issues to the proper authorities. And, I appreciate that Toyota has taken a proactive step rather than being forced to do something. And, I appreciate my number one (#1) Toyota dealer in Minnesota (Walser Toyota, Bloomington, Minnesota).

 

Received my recall letter and took my car in. The part needs replacing but the parts will not be available for a month or so. Toyota have known this recall is happening. They know there will be a need for availability of the parts which need to be replaced. Why do these parts need to be ordered from Japan and not already in local stocks?

Just goes to show that any large bureaucracy is inefficient.