NHTSA Tracking Braking Loss on Prius Hybrids

Hi

I'll tell you my story and good luck with your final decision.

I had researched the 2010 prius for well over a year and knew it was going to be my next car --- i had shopped for 8 months from April 09 to November 09 - then for personal reasons decided to wait until spring of 2010 --- then my car started having problems and was just about at the 100000 mark --- so then I fell a little pressured to make a decision - but I was well educated on the prius and pricing because I already had shopped - so I made the decision to buy and literally the next day I started reading about the "braking issue" and became very apprehensive --- but the fact was I had already taken 3 Prius's overnight on test drives 3 separate occasions. So I took it again and did everything I could to try to simulate the issue in the siver prius iv w solar I was going to purchase --- nothing..... I bought on 12/31/09 - I have about 800 miles and no regrets. It was a business decision at that point for me - if I didn't feel like a needed to do the transaction at that time I may have waited for resolution before buying but on the other hand I am very happy with the decision I made.

Best of luck with your decision!
Gail

 

So since you can't or won't back up your claim, then you have no credibility and are not believable. Your unsubstantiated posts leads me think you are here to stir up trouble.

Take it however you want, if it writes like a troll and behaves like a troll then.....

 

HOW BAD ARE THE BRAKES

We polled the PriusChat membership for 30 days and found:

	Column 1	Column 2	Column 3
0	count	%	description
1	56	58.3%	no brake issue
2	23	24.0%	monthly
3	12	12.5%	weekly
4	5	5.2%	once per day

* http://priuschat.com/forums/gen-iii-2010-prius-main-forum/74199-poll-prius-brakes-problem.html

We then asked how severe is the brake problem:

	Column 1	Column 2	Column 3
0	count	%	description
1	56	44.1%	no brake issue
2	18	14.2%	scary
3	24	18.9%	can live with it
4	29	22.8%	no big deal

* http://priuschat.com/forums/gen-iii-2010-prius-main-forum/74199-poll-prius-brakes-problem.html

WHEN DOES IT HAPPEN

We've asked folks to give us Google Map locations of where this problem occurs and so far, we only have:

* there is a third but I don't have it handy, yet.

We notice that in two Google Map documented cases, there is evidence of parallel, road patches. The third was a street badly in need of repaving. Two of the three are at the bottom of descent and the other a right turn lane approaching an intersection.

OPINION

We continue to investigate the problem but are hindered by the low ratio of responders providing Google Map or Google Earth coordinates for where this happens. So far, only 3 location reports out of 71 who reported having experienced the event. These are observations by 2010 Prius owners and not the friendly, chatty, but otherwise useless gossips.

Bob Wilson

 

Come on folks, lets play nicely together. It's obvious that the Gen III Prius has a perceived braking problem. I say "perceived" because it is possible that the same behavior is perceived by some to be a problem and perceived by others to be normal behavior.

The thing about perceived problems is that they are *real* problems to the perceiver. If your car makes you uncomfortable, then it's a problem, even if the car is performing to spec. Customers are funny that way - it must be something about paying large amounts of money.

So here is where we stand:

1) This could be a real problem that affects some Prius but not others.

2) This could be nothing but a funny sensation that bothers some drivers but not others.

3) Some drivers may have never hit the right set of circumstances to cause the problem.

4) Some combination of the above.

Please try to be civil to your fellow posters. Bashing someone is not going to change their opinion, nor will it generate any useful information.

Tom

 

Exactly, which is why we polled the membership.

The next part addresses the question of where does this happen:

Now if we can get some more locations besides the three already posted, we may be able to figure out what is going on. This is called problem diagnosis and begins with observations, not idle speculations.

Bob Wilson

 

Since we have a few locations, can other owners go there and try it out and report back? Bonus point if you record it in a video.

 

One concern mentioned is through a post by Danep, as follows:

Additionally, as another poster pointed out, this failure could result in unintended travel of approximately 20 feet - I don't know how you couldn't consider that severe.

This comment seems a bit extreme, and it would seem that maybe when the poster fealt the temp loss of brake feel they delayed a response??

I have 3790 miles on mine, fealt it once on a particular road separation between a bridge overpass and the road surface.

I can on occasion reproduce this depending on speed and braking, but know what to expect, thus the harder application to the brake pedal. My travel is less than a foot at that whole time.

Just seems 20 FEET seems a bit much for travel, but then again it's perception it's 20 FEET possibly????

 

There are a lot of engineers and analytical types within this forum and I think they enjoy the challenge of trying to diagnose this problem, and that's fine. But if this is really a problem, then I think it's going to be defined in automotive lab conditions and the solution will be forthcoming from those results.

You have a wide spectrum within this forum. Those that think they have experienced the sensation and think it's a problem, those that think they have experienced the sensation but it is so rare, and just a harmless part of regenerative braking, and those that have never experienced the sensation.

The only thing I would ask would be that everyone keep an open mind to everyone else. If you've never experienced the sensation, that doesn't mean it doesn't happen or exist, if you have and think it isn't a problem, it doesn't mean it isn't perceived as a problem by others. If you are experiencing it, it doesn't mean that it isn't just a personal adjustment that the driver must make.

I think those that have experienced it, and are concerned need to report it. I would hope nobody ever gets hurt or injured as a result of this sensation or problem.

Unfortunately, like medicine, sometimes the problem has to get worse before a diagnosis can be made and real treatment begin. Right now the NHTSA has just a handful of complaints, right now Prius Chat has really just a handful of owners saying they have experienced the sensation....some are alarmed...some are not.

Doug Coleman said 77% of 2009's Prius sales were 1st time owners. That's a lot of people pressing Prius brakes, under a lot of different conditions, for the first times in their lives. If its a repeatable condition or sensation and/or a real problem we will hear about it.

It's my opinion that often polls of this membership, within this forum are waste of time. This is Prius Chat, so by definition it's filled with a majority of Prius Supporters, Owners, and Champions of the Technology. So if you ask this membership a question like "Are Prius Brakes Bad?" then of course the majority are going to respond No, they think they are fine. Add to that, that at this point, the reported problem is random and not being reported in huge numbers and what do you expect?

With a large number of 2010 Prius being sold to a large number of first time owners the real test condition is the real world. So in absence of automotive lab and/or test track, we are all relegated to "idle speculation". The addition of more information is always helpful, be it photos of the area's inwhich this phenonema occured or simple communication of the events as they unfolded. I would be interested in some idea of how many of these complaints are coming from 1st time owners as opposed to 2G owners that upgraded. If all these complaints are coming from 1st time owners I think it lends significant credence to the idea that this is a "normal" sensation that new owners just haven't adjusted to yet.

My gossip filled idle speculation is that this "problem" is most likely the actions of the regenerative brakes system and the micro-second delay in switching from regenerative to friction. My further idle speculation based solely on reading the posts of those experiencing the problem, is that it might have much to do with sensors in the braking system being triggered when hitting uneven or rough spots and this may happen more often with 2010 as it has been reported that it has a stiffer suspension as well as more weight and horespower.

Could all my idle speculation be wrong? Sure. You bet.

 

Sorry but "enjoy" is inaccurate because some of us have 2010 Prius and family members who also drive our Prius. We have 'skin in the game' so it would be more accurate to say:

There are engineers and analytical types who diagnose problems.
​

This is factually accurate.

So the first step in diagnosis is to understand who actually has the problem, which led to polling the membership. Now that we know who has seen the problem, the next part addresses the question of where does this happen:

Now if we can get more locations besides the three already posted, we may see a pattern. We'll do it open book ... a 'teaching moment.' Take good notes because for some, there may be a test. <GRINS>

Driving into work this morning, it occurred to me that photos of an 8 ft., 2x4 laid on the two patches would give us enough information to tell the spacing and possibly the vertical dimensions of the two patches. There are multiple combinations of:

• bump minimum/maximums are the same as wheel axis distance
• bump minimum/maximums smaller than wheel axis distance
• bump minimum/maximums larger than wheel axis distance
• bumps are convex, y{1} and y{2} inches
• bumps are concave, y{1} and y{2} inches (same as above with negative signs)

We are seeking facts and data, physical observations. We already have plenty of opinions and repeats of opinions, ad nauseum, so we don't need any more of that.

Bob Wilson

 

Bob, I think your quest for information admirable. However, I think there are many things happening in this forum at once. For some it's a search for a solution, for some it's a desire to communicate what has happened to them, for most, I think, it's still at the point of defining if this is a real "problem" at all.

The truth is the reality of a forum invites opinions and unfortunately sometimes the repeating of opinions...ad nauseum. It's the nature of the beast. There will be no getting away from it.

I think many people appreciate not only within this thread but many others, the information, graphs, and informed opinion you bring to the table. I know I do. When I say some people "enjoy" I think that is fair, I know owners with families do have a higher stake then I do, at least at this point, but I still say "enjoy" because I'm not just talking about you, there are plenty of owners, with assumably families, that have chosen to ignore or not be involved in this discussion at all. It's still a choice. If you are not being paid by Toyota to do this, at some level I have to assume you enjoy it. While I admittedly am not applying as disciplined an engineers approach, nor gathering photos and poll results, I admit I enjoy the process of discovery, that's why I check in on this thread. It's like a FAA investigator, on one level it's a tragedy, a plane crash, but on another level it's a mystery...it's finding out what has happened and what can be done to prevent it re-occurence.

Everyone is going to approach this with the skills, POV, and abilities they have personally. Ultimately, I think we need everyone. Complaining owners, supportive owners, analytical types that diagnosis problems and "idle speculators" that are simply musing as to what the problem might be.

Anyway, I appreciate your educated, diciplined approach. I fully admit that my opinions are formed out of the rather limited feedback of what I can read from these threads...which includes your information. If I'm responding I strive to not make it a repetition of the same opinion over and over.

Within a "serious" thread, and I take this one seriously, I try to keep my opinion at least grounded. But I also admit that in a lot of other threads, I don't always take things seriously. I've noticed I'm not the only one, and I like that about Prius Chat.

Anyway, in short...whether your personal motivation for inquiry is based on ownership and concerns about your safety and the safety of your family, or it falls anywhere along the spectrum of diversity that exists in a forum, my hat is off to the engineers and analytical types. You and others. I'm way too much of day dreamer, just leave a little room for the idle opinion, or the "uneducated" guess, because sometimes that's exactly where the right question or right answer comes from.

 

Bob,

Right on. :rockon: Good of you to try and put some meat behind all the rummors. The more one can quantify, the better chance there will be in assessing how much of an issue this really is? You know, it's like Toyota's/Lexus well publicized problem with the floor mats... It's a problem for some, but not for most.



PS Did not respond to the poll, but I've had no problems.

 

Ok,

Here are the images I currently have available:




It looks like we need:

• one side of tires - all four are not needed
• both tires are needed
• looks like a positive bump is needed

What we don't know it the bump relationship to the tires:

1. longer than axle length
2. equal to axle length
3. shorter than axle length
4. height

Can anyone help on measuring the distances between the dual-bumps?

This also explains why it is so rare. It looks to take two, bumps somewhat precisely apart to replicate.

Thanks,
Bob Wilson

 

Bob,

From the pictures it's hard to say for sure, but they don't look any worse (maybe better) than the pot hole riddled streets around Chicago.

Have you experienced this phenomena? As someone who seems to be more analytic, I would be inclind to believe your view point, than some of the folks who post on here...who (my impression) seem like they've never driven a car before, and/ or get concerned at every little thing.

I was going to start a thread entitled, "My window is dirty, what should I do"? With a sub-heading of: " Is this a safety defect, and will Toyota cover this under warranty repair?

But then I thought some people might actually believe me (since, as we all know, everything you read on the internet is true)...and not recognize it as sarcasm. Anyway, my window really is dirty, so I'm off to call Toyota to complain. Maybe they'll give me a loaner?

 

I'm not sure because 'words' can often mean different things to different people. There is one, single pothole near the dog park that gives a momentary, barely perceptible 'ugh'.

I figure the first step is to document what others have reported as 'problem areas.' Then using some lumber, see if I can create a controlled way to replicate it. Then we can do some experiments and quantify what is going on.

Bob Wilson

 

Bob,

Documentation is always good. Documentation from someone that knows what they are doing is even better. Good luck. I have not expereinced what people have described. But I keep trying to duplicate...

 

When I saw the pics, that's exactly my first thought!

 

This one is a railroad crossing. The user reports it happened once when it was raining and they were traveling from right to left:


It looks like an upward grade and given the oil spots on the left side of the track, some folks may be seeing a little 'air time.'

Bob Wilson

 

I'm glad someone pointed you to a railroad crossing. Both my suspected events were on humped rail crossings with broken pavement.

Unfortunately both were while traveling, so locations cannot be pinpointed. It hasn't repeated on home turf. While I voted 'not a problem', experience is still too limited to be certain that I'm voting on the same phenomenon that others are voicing concern.

 

It is not uncommon to see more than one intermittent problem generate similar symptoms. The railroad crossing ... something of a jump ... may cause a similar symptom to the double-bump.

Bob Wilson

 

Well, today marks the two week anniversary of owning our 2010 Prius which was manufactured 11/27/09 (we had a 2005 Prius for about 5 years) and today I took it to a part of the road where there were two manhole covers before a stoplight (about 20 - 30 feet from the light). I did the regenerative braking (slow regenerative braking like I usually do ) and when the car's front tires hit the manhole covers, I experienced what everyone has been talking about; the regenerative braking released and I finished by using the frictional brakes. It was, for me, a NON-EVENT! I have felt this feeling numerous times with the 2005 and there was absolutely no problem stopping the car nor did I feel in danger at any time. If there was any difference in stopping distance, I feel it must be extremely small.

Like I said, the 2005 did this on numerous occasions and I know enough to realize this is how regenrative braking will work at certain times; I felt it more with the 2005 as I used the regenerative braking very slowly coming to a stop and when the car got to a certain MPH, the regenerative brakes released for a micro second before the frictional brakes engaged and I just stepped a little harder to stop the car easily.

So for ME, the experience was a fairly normal sensation that I have experienced before with hybrid regenerative braking under certain situations. Not scary at all and I felt no danger nor do I think it affected my stopping distance appreciably.

Unless others are experiencing something totally different than me, I don't personally feel this is a safety issue. JMHO though. I was concerned about this after reading all that was posted but very relieved to know it's how my two Toyota Pri function.

For what it's worth . . .

<Google Maps>

2/6/10 Update: Since all the news about Toyota admitting there IS a software problem, now I am wondering if the sensation I felt was what others have been talking about and I think my experience probably was not as extreme because it really was nothing. Perhaps I have not felt a more extreme transition but to date, I haven't. Now that I do know there is a software problem, I, of course, want the updated software for the braking ECU so that may car is programmed for the what Toyota believes is the correct transition for the braking behaviour. Like others, I am somewhat annoyed with Toyota for not admitting this sooner to those of us with pre-January produced models but am glad there will be a solution forthcoming.