Prius Brake Recall – A Little More Information

Will the software update fix prevent the vehicle from lurching forward as if you've been hit from behind during hard braking?

 

I don't believe that the Prius "lurches forward" during any braking, with or without the fix. The lurching sensation is caused by a reduction in deceleration (engineers would call this "jerk"). Humans confuse this sensation with acceleration, even though it is not. In this respect the brake fix will eliminate or reduce the sensation.

Tom

 

so basically this "fix" (not my definition since something would have to be broken first) is kinda like "PWR" mode for the brakes.

sorry, but more responsive braking force means a much greater opportunity to overbrake, causing more friction, less regen, so it simply makes it easier to get worse mileage.

i wonder how much of the mileage improvement over the classic Pri's is attributable to the regen extending below 7 mph?

this software adjustment will imm, cause the mileage improvement to be less in most circumstances.

 

It should reduce the brake pause:

The brake pause in this case was about 700-800 milliseconds.

If you have an iPhone or iPod Touch, you can get accelerometer software and measure and document this "lurching forward."

Bob Wilson

 

Exactly... Many previous gen owners such as yourself mentioned that the same anomaly occurred in the gen II BUT not as bad. Yet the G3 appears to be more intense and in about a 1/2 year Toyota comes up with this patch that the Team describes as improving the brake feel and stopping distance. It seems that kind of improvement would have something to strive for in the previous four revisions. Unless there is a downside to it (e.g. puts the PSD in jeopardy). That is what I would like to find out.

Or I guess the other possiblilty is a poor brake engineering group.

Thank you and Bob for the thoughtful posts.

 

Speaking as one engineer to another the only thing I'd add to your statement is that in this case the job could never be done if "every" customer must say "its done".

There are obviously some who will never say "its done" and cannot or will not ever be satisfied.

 

While I fully understand that internet sites and forums of discussion aren't official means of registration of concern for Toyota, I disagree with the contention that they cannot help you diagnose the issue.

Since Prius Team obviously does monitor Prius Chat albeit perhaps informally and unofficially I think history has shown that the relationship has been symbiotic.

In brighter days an appearance (post) by the Prius Team was met with almost a screaming 1960's like adolescent Beatles adoration. You guys were like rock stars.

You have to admit you have used feedback gained from this site. So again, while I understand this isn't an officially sanctioned inlet for complaint or registration of complaint and probably shouldn't ever be, why are posts and threads at least informally not an avenue for diagnosing issues?

I would think think Prius Chat an excellent place to perhaps see a wave as it starts to form. This site was struggling to define and resolve the "braking issue" with the 2010 Prius long before it became an official recall or an officially recognized problem.

If Toyota's intentions are listening to customers more closely and responding more quickly then they SHOULD be keeping an eye on sites such as Prius Chat and others.

Speed the gap between something being "unofficial" and thus unrecognized and something being "official" and recognized.

For instance, there is evidence in numerous threads on this site that you have an ocassional problem with how the brakes in the Prius react when backing up. Jerking, grabbing...

There also is some evidence that the engines after sitting for a period of time are starting roughly and shaking.

I'd just hope that Toyota Corporation actually become pro-active in response and not use "unofficial" as an excuse to cherry pick what issues they address.

Maybe a specific link from this site that goes directly to an "official" Toyota problem registration site would be something that could be created and be beneficial to both Prius Chat and Toyota?

I don't know what the legal implications of a 3rd party, Independent Site being unofficial and independent having an official link to a Toyota site would be but speaking to Prius Chat...I'd think it would be helpful. Mutually beneficial to both parties.

When a Poster appeared with problems, not only could we have the debate, discussion and evaluation that happens within threads, but "we" the collective conciousness of the Prius Chat community could also say...click on that button in the corner and "officially" report it to Toyota.

Perhaps I'm missing something in regards to independence, and sponsorship. Toyota might have to pay for this. Hey...it's worth it. But it's something as an individual participant within Prius Chat, that I'd like to see.

 

If the brake fix for the G3 Prius shortens the time and pedal pressure required to activate friction braking, this will necessarily reduce kinetic energy available for regenerative braking. Kinetic energy will be lost to friction and heat in the mechanical brake components, rather than recaptured as regenerated electrical energy in the battery. Doesn't this mean that the brake fix will reduce regeneration of energy on braking, at least, slightly reducing fuel economy?

 

Just like many have said that there has been a bit too much hysteria in the media about a (relatively) minor braking issue, let's not get too carried away with nit picking on the mpg. Roughly 99.99% of the time you are braking nothing changes. It is only after you have gone over a pothole, slick spot or whatever that you will experience a fraction of a second difference in the amount of regen (if any).

So let's say (guess) that regen gets you close to nothing on highway mpg and 5 mpg on city driving. You'll still get 99.99% of that 5 mpg. Even if it is only 99%...you are not going to be able to detect the loss.

3PriusMike

 

Good engineering uses 'back channel' communication systems ... informal ones that allow folks to discuss things without 'getting their panties in a wad.' We use magazines, papers, and symposiums (especially good over food and beverages.) It is half art and I'm by no means skilled in it. But it often lets folks share important stuff without getting the lawyers involved.

We can always use the formal channels but they can quickly become clogged or worse. So it is important to communicate both up front as well as back channel. I know it may seem unfair to those who "don't have skin in the game." But you know, we all need to get some sleep sometimes and a timely joke makes it a lot more fun.

Bob Wilson

 

Thanks for the detailed reply.

I suppose I'm oversimplfying. I do realize the impossibility and even the danger of Toyota reacting or trying to react to every post or thread that may appear, that suggested a mechanical or safety problem. I understand that within the auto industry there is a protocal and accountability that must be maintained for everyones good. My suggestion was never that "Prius Chat" become the well spring or source for the process of documentation of a potential problem, I would never want that to happen. As you point out, it isn't the proper venue and I think it would hamper the social community that exists within Prius Chat. These are just my opinions.

What I've noticed after months of observing and participating within Prius Chat is that it seems that people often treat a problem with an automobile in much the same manner many people treat a medical ailment. That is, when some people feel a pain, they often turn to co-workers, friends and colleagues first, for advice. Maybe they should go directly to a doctor, and seek the official diagnosis, but there is something reassuring in communicating in a community of "like" others. Maybe with the hopes that you'll save yourself a trip to the doctor in the first place.

The recent "brake issue" is a good example. In most cases it seemed new owners that were experiencing the sensation reported it here first, even before taking it to a dealership, or reporting it in any official manner.

In his recent statements concerning efforts of Toyota to repair it's image Akio Toyoda said: "We fully understand that we need to more aggressively investigate complaints we hear directly from consumers and move more quickly to address any safety issues we identify."

This is what I mean by "speed the gap" between a problem being unoffical and unrecognized and thus unresolved, and official, recognized and resolved or at least in the process of being resolved.

So while I do understand the importance of documentation, gathering proper information, and following needed channels of accountability and transparency, if Akio Toyoda's statements are to be taken as anything more than nice sound bites for the media Toyota imo must be careful not to fall into a Joseph Heller-Catch-22, process of "The problem is not a problem because it's not officially a problem because the customer hasn't officially filed the official report within the official chanels....you get my point.

So I am oversimplfying. I am also taking liberties with what may or maynot even be possible. I notice on the front page of Prius Chat under "Official Sponsors" Toyota has a link to there own website. Right now it offering information to owners about the recalls. My suggestion is far simpler than overhauling the standards of protocal needed, my suggestion is why not a clear and simple way from the internet, from Toyota where consumers can "start" the process of documentation of a problem? It would be nice if this could be linked from sites like Prius Chat. What I see now, is I can hit a link from Prius Chat on the front page to be taken to Toyota to get information about recent recalls but there is no way if I'm a owner with a problem or perceived problem that I can hit a link and report a problem. Or at least at this point there is no simple way that is widely known.

Again, using the recent brake issue as an example, within most threads it seemed the only avenue for most people became "take it to a dealer" or "File a complaint with the NHTSA". Which like seeing a doctor with a medical ailement, might be the right thing to do but something I think people are hesitant to do. Furthermore a big flaw with the brake issue, was as long as publicly the issue was unrecognized by Toyota and since it was a calibration issue that needed a software change, people could/would take it to dealership service departments only to be told that the brakes were operating normally. The Catch-22,--"Your problem isn't a Problem because we haven't officially recognized it as a Problem".

Anyway, why not make at least the documentation of complaint from consumers as easy as possible? From Toyota's P.O.V. the process of definition and implementation of remedy could still be controlled and made to fit the industry standards of accountability. It would just be a "new" inlet on Toyota's end, that could if wished use sites like Prius Chat as the genesis portal for reaching consumers.

Sorry, I like to write. If you've read this far thanks.

 

There are rare and intermittent problems that in the past, submitting a formal complaint would not have worked. Certainly in my case:

• sticking accelerator - not having experienced it, I couldn't submit a report. I had one NHW11 accelerator come in with a bent cam-follower but I straightened it and never thought of submitting a complaint. At PriusChat, we had one NHW20 user pursue the accelerator problem a year or so ago long enough that we saw a photo of his all-weather mat. Otherwise, the frequency was very rare and we only had a sprinkling of 'hit and run' posters who never stuck around long enough for us to get to that level of detail.
• "check engine light" on fuel exhaustion - I've done three fuel outages and only two others have reported similar experiments. Now I still believe the NHW11/NHW20 are right to raise at least the "check engine light" because it lets the driver find a safe place to park using the traction battery. The ZVW30 does not and a fuel pump failure would be a classic way to show the problem. But our informal discussions in PriusChat have given me a clue about how to submit my report so it won't be easily dismissed with "it meets the design requirements" . . . so too did the ZVW30 brakes.
• brake pause - until last week, I didn't realize the rain-slick, Huntsville streets might be masking the braking problems the A0B fixes. Being a curious guy, I picked up some accelerometers and have engineering data to back up a complaint ... if warranted. But first I have to retest the brakes and see if A0B tames Huntsville streets.

Toyota USA can't formally use PriusChat except to give an early warning, an alert, that some of their enthusiastic customers are seeing something interesting going on. Call it 'rumors' or 'buzz' or 'back channel', it means we can talk-technical without putting someone's employment on the line. In contrast, a formal complaint to Toyota or worse, the NHTSA, gets tracked (aka., ISO-9000) and is likely under some time constraint to be answered ... even if badly.

Going back to my concern about the "check engine light," since last summer, there has been an attitude change. But I've not filed a formal complaint about the "check engine light." Now I have a clue about how to approach both organizations from the safety standpoint ... leverage.

There is one other potential, latent design defect and of course the "Bell the Hybrid" effort that has or is starting to draw my attention. However, let's see if we get any 'repeat' postings at PriusChat. But if you haven't noticed, I enjoy problem diagnosis.

Bob Wilson

 

I think I've probably overstated my opinion. You have to know when to just shut up. But just to clarify I think Toyota USA could formally use Prius Chat to the extent that I don't see why they couldn't have a link from Prius Chat to their own website, where they could offer a process of problem definition and register.

It comes down to me to the simple fact that sites like Prius Chat are where Toyota's customers and owners congregate. If they care about reaching them, and really listening to them then they need to be here in some form or another, even if "officially" it's only an informal link to there own official site.

I've applauded and I do admire your attempts to diagnose problems within Prius Chat. But sometimes I think it's just personal skills and P.O.V.. You are approaching events as an engineer and have even admitted to being distract by the inevitable repeat of opinion and buzz that happens as a natural process of a social forum. I think in this case, it's the "buzz" Toyota needs to learn to utilize in a better way. Sure monitoring Prius Chat can tell you that a lot of owners would like an extra cupholder, but it can also tell you a lot of owners are having brake sensation issues.

Also I don't think we should fear formal registration of complaint. Whether it be with the NHTSA or Toyota, or both. Whether this resulted in someone losing their job or a clock begining to tick on resolution. The truth is, as harsh as it might sound, if a flaw or defect is big enough or damaging enough to the company, perhaps somebody should lose their job. And as far starting a clock ticking on resolution, that also might be perfectly valid.

I'm NOT here to bash Toyota. They've had enough. But you do have to at least wonder how much of this pedal recall, and The Prius software update, really is a result of pressure from The Japanese government and growling from the NHTSA.

I'm not versed or familiar with the minutia of law concerning complaint registration and problem resolution within the automobile industry. Infact, given recent event's I'm sure this is going to be hotly debated and argued. However, I think Toyota should learn from this, that when it comes to complaints and problems it's better to be as pro-active as possible than reactive. imo Prius Chat could be an excellent tool to utilize in an effort to be more pro-active.

I will shut up now.

 

They could have, but they didn't. There have been rumbles about brake issues on PC going back to at least 2007, with no action from Toyota.

To borrow from The Electric Me, it seems to be a classic example of Joseph Heller's Catch-22:

And now Toyota has got an 8.1 million vehicle recall on their hands.