NHTSA Tracking Braking Loss on Prius Hybrids

Efusco,

One could make a very good point that floor mats are not a safety issue either if installed, maintained and used properly...

Toyota's looking into this matter. I'm anxious to see if they determine it's a potential safety issue that might require some braking adjustments or not. I'm glad to know they're investigating it because I've said many times I think it's a POTENTIAL safety issue for some- in fact it seems a helluva lot more like a potential safety issue than floor mats would be- and we all know how that went. Car manufacturers need to be proactive in listening to their user base and not reactive after a tragedy occurs that COULD have been prevented.

 

There was an article in today's Detroit Free Press about Toyota being the leader in safety recalls for the first time this year. A reader posted a comment about the potential 2010 Prius braking issue, so yes, word is spreading.

I will be traveling over railroad tracks today at 55 MPH and if traffic and conditions permit, I will try to recreate this at 55 MPH.

I have never seen the VSC or TRAC light come on when this occurs.

We took a different route and did not travel across the RR tracks at highway speeds.

 

To show how something like this can get blown totally out of proportion, I was parking at Lowe's Home Improvement store and a guy parks beside me. Walking in he asks me if I have had any problems with my brakes and if I am aware that Toyota has a problem with the brakes on my car, that it is a safety issue and Toyota is not acknowledging the problem. He says that all owners really need to be made aware of this problem.

When I explained to him that I was well aware of the problem due to PriusChat and that I did not think there was a problem, only that the brake system on this car performed differently due to the regenerative braking system in conjunction with the traction control, ABS system, etc. Owners just need to be aware of how the system performs in different situations, similar to when ABS systems first came out.

I asked him if he owned a Prius and he said that he did not but he had driven a friend's Prius !!

After this, he wanted to know how I liked the Prius and wanted to know all about the technology. He was interested in looking in to one.

 

I'm glad to hear that. I don't think the braking issue should deter anyone from buying the car at all. I do think that anyone buying it needs to be made aware of the effect and hopefully it will alleviate the shock for users the first time it happens.

I do also appreciate that Toyota is looking into the matter. It would be great if they could make some kind of firmware adjustment so the transition from regen to friction happens without any hiccups when braking on bumpy surfaces. Then everyone could be happy.

 

Because of the battery current limit, maximum possible regen braking force is inversely proportional to speed. So at 60 mph, regen-only braking must be very light. That is why I mentioned earlier that regen-only braking from 60 mph results in a very long braking distance, approaching 1000 feet at best. A constant-g braking profile will require an even greater distance.

 

As an ower of two 'different' hybrids that do this...I think that the manufacturers should include this in the owners manual. Both my wife and I have adjusted to this happening however it still 'stuns' a little bit when it actually does happen. It gives you the 'feeling' that the car is picking up momentum.

 

For the non-engineers in the group, here is a quick explanation of this:

The power that the battery can absorb is limited to some maximum value. In the case of braking, power is equal to braking force times the distance traveled in a given time. Since you travel faster at higher speed, the braking force must be lower to keep the power at or below the battery limit.

Tom

 

Glad to see this on the forum. I caught this topic on a crawler on the news a quick search lead me here.

I have on 06 pushing 50k and this is definitely a problem with this car. I can replicate this at will on any washed out surface. The ABS light always comes on when this happens. I described the problem to the dealer at the last service and, (since it's under warrantee), there was of course no problem found.

This began happening at about 35k for me. My next test will be the struts. I suspect they're not holding the tire to the road as they use to.

I spent the last week on ice playing with the problem. I've never heard the comment about mud, tracks and such with ABS but it makes some sense. I believe you should know you're vehicle but also understand that most people just drive cars.

I'll make a point to report it on every service to get it on record.

 

I just find this to be non credible. I can barely if ever get mine to do it. I just don't believe it because my cars both my former 07 and now my 10 have to be coerced into making this happen by doing something I don't normally do. If you can do it on any washed out surface, then it may be hyroplanning that you are taking about.

 

That's why the original article used words like FAILURE and RISK. There is a clear attack on Toyota's credibility at play.

We've seen this same behavior in the past from competing forces. They've been somewhat successful too... getting the casual reader to believe what they claim at face value without question.

It does wonders from publishers too, since people thrive on issues like this. So, they keep pushing to draw more attention to themselves, which contributes even more to the concern growth.

Study Prius history. You're in for a surprise if you thought a topic like this was anything new.
.

 

John,

I agree. This is obviously a disinformation campaign against Toyota, and just the latest in a long series of such campaigns. It just shows how desperate U.S. car makers are. People are very naive if they they think that such things do not happen. Many journalists are paid to write propaganda for various commercial interests.

I have a 2005 Prius and have noticed this split second sensation of loss of braking power many times when I drive over a sewer cover while braking. I expect it now, just as I expect slight shudders when the engine shuts on and off. It has never been a safety issue. At most, it may alarm people with bad nerves. I would like to know if there has every been a documented instance of an accident caused by this so-called "brake problem".

 

Well said. I completely agree. I even think that PriusChat gets taken advantage of to foster these attacks. Get a number of aliases to post here, and then point to the threads from a supposed "news" outlet. They needed some sort of reference to point to, so they create it.

"I would like to know if there has every been a documented instance of an accident caused by this so-called "brake problem".
If there were, they would be in the article. Instead they had to resort to creating something to reference. A so called circular reference.

 

Just got an e-mail from my supervisor citing the Prius "brake problem" story from MSNBC. I already replied and told him I tried it and it doesn't bother me:

Bob Wilson

 

IEEE Spectrum: Automated to Death

 

If you carry a bowling ball around in the footwell of your vehicle that's a safety issue. Should vehicle makers be responsible for every stupid thing that an operator might do? More and more the answer is..
'YES, common sense is being discounted. Personal responsibility is being shunted to the rear. Autos and other consumer products have to be designed to meet the maximum threat situations caused by the dumbest amongst us.'
Case-in-point the stupid Lexus dealer in San Diego.

Becker wants his money back because he doesn't like the feel of his vehicle. He claims that for him personally he feels that there is a safety hazard present despite any evidence or data to support that position. It's his feelings only. The evidence and data point in the exact opposite direction, there is no safety issue at all. From his comments herein I see him attempting to coerce Toyota to give him his money back, nothing more. It's all about the money, it almost always is. Toyota refused to do that so he made a Federal case out of it.

As a New Yorker myself I recognize the species.

 

DeadPhish
I am 100 percent with you on this one I smelled a rat as soon as I saw the OP raised some of the media.
It does not take a brain surgeon to figure out Toyota has deep pockets, so the spilled coffee lawsuit has been done before, now what can one do with this one ??

 

I challenge all posters here who have experienced the brake loss, to document the conditions. I want to take my car out and verify it and I am sure others want to do the same. If anyone else including first time posters want to declare this as a problem, let us document it. Otherwise just posting that it has happened to me all the time etc... at this point does no good.

Let us document when where and under what conditions it is happening and a number of us will try to reproduce the event.

So BigHouse and others who can make this happen all the time, go do it and document the conditions and type and dimensions of obstruction (pic would be nice) and some of us will try to duplicate it.