Toyota Acknowledges Design Problems In 2010 Prius Brakes, Modified Models Built After January

Re: The Woz Knows What He's Talking About- Toyota Admits Software To Blame For Prius Problems

Where in the manual does it say NOT to hold the lever in the resume/accel position until reaching the desired speed? The way I read it, you should hold it either up or down until reaching your desired speed.

Again, if the car continues to accelerate after releasing the accel function, that is a serious safety issue.

 

I have yet to comment on this subject as well until now. I have experienced brake-loss maybe about 10 times since getting my car in August. There was maybe 2-3 of those times that I ended up coming to a stop much closer to the vehicle in front of me than "intended." This is an issue, and I certainly could have hit another car (granted at a low speed) that would have screwed up my insurance rates & cost me $ for repairs.

It simply needs to be addressed. I just did my part & spent 5 minutes filling out a NHTSA complaint. I feel that is my duty to do so and I will just take whatever actions Toyota recommends.

For those who want to simply file a complaint as well:

https://www-odi.nhtsa.dot.gov/ivoq/Complaint.cfm

 

I think the real trick is to extend the distance from the cars in front of you. If this happens, and you are far enough away from another car, you at least have time to regroup and continue braking. Maybe, Toyota will compensate us some how. Bring the car in for an oil change and we will do the fix and service for free. I'll bet Honda is sittng back enjoying all of this.

 

Toyota should try to make one fix that takes care this brake issue as well as the super annoying issue where it feels like brake-assist randomly kicks in when driving in reverse. You press the brake one inch and it brakes as if you slammed on them.
The car has braking extremes of non-responsiveness or over responsiveness depending on the situation. Very glitchy.
Maybe both problems are related.

 

Re: The Woz Knows What He's Talking About- Toyota Admits Software To Blame For Prius Problems

It's in the section on Adaptive Cruise Control, where it tells you that your speed is limited by the traffic in front of you. When the road clears, your speed will return to its set value.

The problem isn't with holding the CC lever. The problem is with selecting an excessive speed which is held back by traffic. When the traffic clears, away you go.

Tom

 

Re: The Woz Knows What He's Talking About- Toyota Admits Software To Blame For Prius Problems

Unrelated. How could you possibly think these are the same issues?

Tom

 

It happen at highway speed to me, I was slowing down 10m behind the car in front of me at around 80km/h. Both front wheel hit a large pot hole and my car dat forward at great speed while the car in front kept slowing down. I brake hard and able to slow down when I was 1m away from the car in front of me and nearly get my pant wet!

I would have had an accident if I react just a little bit slower. This is not acceptable, it will sure lead to accident in many cases!

 

But the problem is if you're in an uncontrollable situation that could cause an accident.

 

This question has been answered many times. In short, normal braking on the Prius is regenerative. Hitting a bump or slick spot will cause the skid control to release regenerative braking and switch to friction braking where ABS can be used. The transition is not as smooth as it could be. It appears that the friction braking comes in a little light, requiring the driver to increase brake pedal pressure.

Tom

 

Re: The Woz Knows What He's Talking About- Toyota Admits Software To Blame For Prius Problems

He waited till it got up to 90 before hitting the brakes? Was he going 80 when he started, or was he testing it to see how long it would continue? Hard to believe he was trying to get from 50 up to 60 and it went another 30mph before he realized he could just tap the brakes.

My guess, knowing that he's a software weenie, is that he was testing it to characterize the nature of the bug. Like maybe holding it in Accelerate from 25 up to 65 and then waiting to see how far it went before the stacked up acceleration requests were cleared. He did say that luckily he could just tap the brakes, so I think this would have to be classified as controlled rather than uncontrolled acceleration.

 

I'd label it "a proven quirk". We're driving the most intelligent car around. Yes, the news is all over it because it's readily sensationalized. The number of actual accidents is miniscule; drivers and dealers have to acknowledge there are small idiosynchracies. Press harder if you're not comfortable with what's happening:the brakes WILL work. And if you suffer prospective buyer's remorse, you can always pull your order.

 

It hasn't been proven that there is a specific driving speed that is a cutoff point for the issue. Pot holes are more common in the city than on the highway, so more people notice the problem at city speeds.
People have posted that they had the issue after hitting potholes at highway speeds.

 

There isn't a cutoff speed. As you mention, you don't normally do much hard braking at high speed. Likewise, hitting a pothole or slick spot at speed doesn't make any difference if you aren't braking.

Tom

 

Re: The Woz Knows What He's Talking About- Toyota Admits Software To Blame For Prius Problems

Is that what the Woz was referring to? Do all cruise control versions have this or is it only in the collision avoidance option?

If this is what he was talking about, then if you were cruising at 60mph and were slowed down by someone in front of you and you changed lanes and it effectively "resumed" back to your original speed, I'd call that correct smart behavior. If you accelerate up behind someone and it stops the acceleration, but you keep holding accelerate, and it stores the accelerate requests and executes them after you change lanes, that's pretty questionable. Both on the part of the driver and the cruise control.

 

qbee42 pretty much describe my conclusion on the brake issue saga.

Besides, Toyota's public statement is explicit in stating there is a "conflict" between regen brake and ABS software(s).

Now, allow me to try to explain why this tends to occur over bumps or manhole cover:

Manhole cover usually provides significantly lower traction to the tires as compare to avg surfaced road. When braking over the cover, slippage may occur even at low speed (say <20mph) and this is when ABS kicks in, screwing up the regen-friction brake control in the process.

Walah! We now have the "unintended acceleration" sensation under a second!

As for hump, well, tire slippage could easy occur on the descending side + tendency to apply brake when going over one.

So now, who's going to test out their latest post-Jan'10 batch?
Now is the good time to get Toyota's service attention.

I am pretty sure they will be very responsive to your complains during this period.

 

Re: The Woz Knows What He's Talking About- Toyota Admits Software To Blame For Prius Problems

Again, I'm going to try to replicate this phenomenon the next time I have our Prius on a clear highway. I'll also try it in our Lexus RX400h. I'll start the acceleration around 45 mph and release the lever around 60-65 mph. I certainly won't let it accelerate to 90+ mph, excessive speeding penalties here in VA are extreme.

I normally only use the accel feature for small adjustments after I've set the initial speed. I use the resume feature where I've had to slow down considerably (such as a toll booth), I just hit it briefly and it accelerates to my previously set speed.

Also, again, if the acceleration continues once the lever is released (using the accel feature, not resume), I believe that is a significant safety issue.

BTW Bob, I'm coming to visit you. We're supposed to get over a foot of snow beginning tomorrow. Kauai is one of the most beautiful places on earth and has great golf. I can probably find a flight out of here today or tomorrow morning. Can you pick me up at Lihue airport? If you could make tee times for us at the Prince Course at Princeville, the Kiele Course at Kauai Lagoons, and Po'ipu Bay, that would be very helpful. See you soon!

 

Re: The Woz Knows What He's Talking About- Toyota Admits Software To Blame For Prius Problems

well before posting stuff like this you might have wanted to check here as we had lot of threads about it.

it is Adaptive Cruise Control, it slows down if the car is in front of you and resumes when car moves out... you can set it to 90 mph, and it will resume to 90mph when road is clear... Nothing more than that...

 

I'm interested to know how Ford does braking in the Fusion Hybrid and how much that differs from the Prius.

 

Re: The Woz Knows What He's Talking About- Toyota Admits Software To Blame For Prius Problems

It's on the Advanced Technology package.

I believe the problem is as you describe it: the driver can increase the target CC speed while the actual speed is limited by the radar system. Once the obstruction is removed, the Prius tries to accelerate to this new target speed. While this is consistent and technically correct, it might be better to restrict the target speed to no more than the current speed (or speed +5) when speed limited by radar. That would avoid any surprises. It's really user error, but why give users a chance to error?

Tom