Braking switch over potholes issue/non-issue update

I have a 2008 prius, and I've experienced the same thing.

 

What do you mean something you need to address?

As you have noted, there are those that have noticed this phenomenon. Toyota even did a flash update of the software to change the braking feel early in the Gen 3's existence.

But at this point, whether you notice this phenomenon or not, whether it bothers you or not, it's not really something anyone can address.

I've spent years reading about this problem, and hearing the debate. I still bought a Prius. I think the bottom line truth is that The Prius has a different and very specific and unique braking system. It's two systems integrated to work together.

I do believe in the pothole theory. I do believe that there are certain specific environmental conditions that if the Prius should encounter this at the exact moment I am braking, I may feel a split second difference in braking feel. This hasn't happened to me yet, but I believe it is possible.

For 99% of regular braking conditions, I actually find The Prius brakes to be amazingly good. The "Pothole" phenomenon seems to exist, but I think it simply a condition that rarely manifests. It's good to be aware of, and probably requires a little forethinking or "instant" reaction by me as a driver if I should find myself experiencing this happening, but beyond that? I don't see what anyone does to address this issue.

The Prius brakes, are the Prius brakes. If you are not comfortable with that reality, the only way to address the issue, is to not drive a Prius.

 

The official response from Toyota was a 2010 software update/recall. The effect may now be less than it was in the initial 2010 Gen III roll-out. But, it's still there.

Can you or Toyota "fix it"? NO there is nothing your dealer can do.

 

Well, I've only owned my Prius a couple of weeks, and I can't say I have experienced this yet. To me, so far, the brakes on the Prius are great, amazingly smooth and responsive.

But for years before I bought my Prius I read about this "problem". If I felt it was an issue that I couldn't live with, I wouldn't of bought my Prius.

To an extent, I look at it like this. On any car you own or drive, conditions can manifest that can immediately hinder or change braking parameters. Even on my standard friction brake Honda Fit, if I happened to brake immediately while going over a wet manhole cover, I would feel the vehicle "slip" forward over that cover. It just happens.

Evidently under very specific similar conditions The Prius can give feedback to the driver, as the braking system tries to adjust, that unnerves some people.

I haven't had it happen to me. So I can't really say how much it might unnerve me. But I tend to think, knowing that it is possible, and the basic answer being...just keep braking or push down harder, my guess is it won't be an issue for me.

But my point is still the same. The Prius Braking System, is the Prius Braking System. You either accept it, or do not accept it. There is nothing else to do to "address the issue".

 

It is definitely still there, and I find it to be manageable. It did scare me the first time I experienced it because it does feel like the brakes are going out. I will say that in the year I have owned my car that it is something that rarely happens. Electric Me, you can't brake harder during that situation, that is the scary part about it. It is a fraction of a second where you seem to lose control of braking abilities. It does recover very quickly though. It is very strange, but not something I am going to give up my Prius over. I have just changed my driving style a bit to avoid it happening.

 

Well to an extent, I feel I should recuse myself from further commentary. Being as I have not experienced this phenomenon yet.

But I did purchase my Prius, well aware that many people reported this phenomenon existing.

I guess when it happens or if it happens it would personally boil down to how dangerous you actually feel this response is. The Brakes ARE different on a hybrid.

But is it a tangible "danger" or just an odd feeling?

To be honest the first few day I drove my Prius, occasionally at stop lights when I noticed the engine turning off, my immediate subconscious gut reaction was that something was wrong. After all, for my entire driving history, if your car stopped running at a stop light that meant something was wrong. It took me a little while to adjust to the fact that this action and feeling was "normal" for a hybrid.

If there are some specific parameters with the Prius regenerative brake system that produce a similar "scary feeling" but do not create a tangible or dangerous driving situation? I can accept that.

I guess I just continue to drive, aware that it could happen, and then judge on that day when it does happen. Where I live in Oregon, their are plenty of manhole covers and there is plenty of rain. I suspect someday I'll have personal experience in this area to reference.

But once awareness of this reality or potential reality exists? I don't think there are many options for addressing the reality. Either don't live with it, and give up your Prius, or live with it. Or report it to the NHTSA.

So when the OP asks, "Just wondering if this is something I need to address?" My question is how? Toyota has adjusted the software since release of the 3rd Gen. Complaints seem to have diminished.

If someday I experience this? I'll make an evaluation. If I feel it is a condition I can't live with? Guess I'll be shopping for a new car. Otherwise? I'll just keep my eyes open for manhole covers and potholes and the like. Things I believe can affect the braking of any vehicle.

 

The key to the problem the OP is concerned is explained by Rupert above. The only thing the OP can do is be aware of the situation and adjust his driving techniques accordingly. The problem does exist in both the Gen II and the Gen III Prius. It has to do with the way the ABS and the TC systems work on the Prius.

About the only thing the OP can do is try to avoid a braking situation where the roads are extremely rough. I know that sounds next to impossible, but as Electric Me pointed out it is what it is concerning the Prius brakes.

I do agree that the Prius brakes are more than sufficient under normal stopping conditions. I also agree that the Prius brakes will shudder at times if one is braking on a rough surface. I too have experienced the situation and the first time it happened I thought the brakes were going out. It wasn't until I learned about how the brakes on the Prius are designed and operate that I then understood what was happening.

IMO there really is nothing that the OP can do other than try to adjust his driving habits to accommodate the conditions of the road he is driving on. FWIW, the Prius is not the only vehicle that suffers from this anomaly. It does affect many due to the way ABS works on vehicles.

Ron

 

Yes +1,
I always look ahead for any man holes , pot holes or ruff roads and adjust if necessary.

 

I think the important thing is to realize that this problem has nothing to do with the regenerative braking system, it isn't about it being different driving a hybrid. We have a Hybrid Escape and although driving from Georgia to Virginia and back was the first time I had ever driven it an extended period of time, I never once encountered the problem driving it, even when I encountered rough roads and potholes. But, being used to driving the Prius, I sure expected it. It only happens when the ABS brakes engage. Not when you are simply pressing the brakes.

Do I think that Toyota should address it? Absolutely, and I am sure they are. Prius drivers aren't exactly a quiet group. But, to my knowledge, it hasn't contributed to any accidents, just raised heart rates, so I am sure they have many other things on their lists.

 

Sure there is. The OP can write his congressman, mayor, etc. and ask for the pothole to be fixed. And when he does this he can include a check for $200 to get it done.

Oh wait, that may seem like a bribe. He can include a check for $200 as a campaign contribution. And then inquire about getting the road fixed.

 

When I first discovered the problem in my new 2010 I was concerned because it surprised me, by the time the software reflash for the 2010 came out it no longer bothered me. If you are aware of it and know what it is there is no problem. It only happens at low speed on certain kinds of roads, as soon as you feel it you will automatically apply a little more pedal pressure to compensate. Also, it only happens at low to medium brake pedal pressure, if you are making a panic stop with the brake pedal really mashed down it will not happen. It's just part of having an HSD car.

 

First there is no real problem or issue here at all. People just hate the feeling of the ABS pulsing.

The reason it is more noticeable is because of the regenerative braking letting go and the physical brakes are taking over.


Either way the car will stop and with the sytsems in place you will have more control over the vehicle then without the safety systems in place.

Braking or hard braking over rough surfaces like a pothole is a no no anyway

 

I don't think that this is addressable unless Toyota were to drastically reduce regenerative braking. I've experienced this phenomena about a half a dozen times in (4) years. I don't think that braking distance is measurably affected. But it can be very disconcerting. So the danger is to your underwear.

 

I am well aware of ABS pulsing. Frankly, the only cars I have ever driven since the first one I got at 16 had ABS, so I am not aware of how things were prior to the use of ABS. The brake is not pulsing, but rather you lose all resistance for the period of time this comes into play (feels like a few seconds, but probably shorter than that) and the pedal essentially falls to the floor. It is kind of like the feeling you get on a bicycle when you lose the chain. You can keep pushing that pedal all you want to, but nothing meaningful will happen. I am wondering if you have actually experienced this in the first place. I am lucky even after 53,000 miles to have only experienced it a handful of times and always on horribly maintained roads.

 

I've had it happen a few times. Maybe it's different in my model/year. The pedal doesn't drop to floor, it just feels different. In fact, it feels like a normal car (the regen brakes are much "grabbier" than friction brakes) that simply needs more pedal input/pressure. Which makes sense because the computer switches entirely to the friction brakes in panic stop mode or when traction/stability control are engaged. I can only presume that when you're under normal braking and you hit the pothole or whatever, the wheel briefly spins and the nose drops a bit which the computer senses as either a skid or a hard stop and cuts over to friction braking.

I may be a little more used to this phenomenon as in my old Fit (just like The Electric Me), I'd get the same type of thing, just with ABS engaging. Fit was my first car to have ABS so I thought that was expected behavior with ABS. Do other cars not do that?

 

My suggestions to my fiance:

- Allow yourself more stopping distance - don't rush up to an intersection and slam on the brakes. (As she likes to do.)

- If it happens, stay on the brake and resist the temptation to pump the brakes like use older folks learned decades ago.

 

This same thing happens in my 2012 Prius with every pothole if braking at slower speeds. I guess the effect must have been even worse before the recall in 2010. Suppose I will have to get used to it. I usually just remove my foot entirely from the brake briefly, then press down harder until I start slowing. It has kept me safe so far, but what a scary feeling!