Braking problem

I have experienced this frequently in my 2005. I think nothing of it now. A sudden decrease in the rate of deceleration for maybe half a second feels like acceleration, but the car is still slowing. I have also found that the Prius can stop on a dime when necessary due to the brake assist. You get used to it.

 

that because it is acceleration. any change in rate of movement over time is acceleration...

if you are decelerating at a rate of 10 mph/sec and change that to 5 mph/sec. (which would be the same as a reduction in braking effectiveness) that is accelerating.

 

Sorry to digress, but the engineer in me feels obligated to take advantage of this teachable moment - technically what you are describing is "jerk", a change in acceleration. "Acceleration" only refers to a change in velocity, such as "10 mph/sec".

In this case I think it would be fair to say that when you hit a rough spot the car "jerks forward", but it certainly doesn't accelerate.

 

That would be opposite problem to the investigations into unintended acceleration with the electronic throttle systems on the Toyota's.

 

Yes, the unexpected loss of braking, appears to be a serious safety issue.

But, like the "unintended" startup-acceleration, these problems are somewhat less of a threat to safety if one knows about them and can anticipate the conditions that "trigger" them.

The loss of braking is more common, and the "skid" sensor seems to trigger the loss.
Braking while crossing a slippery patch (even small) or a "chuckhole" seems to "set the stage" for the "skid-detection", so be aware.

The "overly-agressive" creep is less well understood, and not yet reproducable. It seems to happen only just after turning the car ON. So, when you just begin to move, after startup, let up on the brake very gently, just a little, and be prepared to stop.
EVEN BETTER: If there is anything that you might run into, or as a STARTUP HABIT, shift into R, D, R (or N, R?) and that might "clear" the condition that causes the "lunge".

Do not let anybody drive your carr unless they know about these two "features", perhaps called "Sensitive Anti-Skid" (SAS) and "Get-Up-and-Go" (GUG)?

 

Yes, I have the Package V with Advaced Tech Packge. I am very concerned about this issue.

When slowing down slight pressure on the brakes and there is rough terrarin or bumpy road. Brakes stop respoding causing the driver to apply greater force to slow down and stop the vehicle.

Yes I belive this is a safety issue a novice driver not aware of the problem can easily hit the car infront if not paying attention.

I have called toyota customer service line to report issue. Everybody having this problem should do the same.

Hoping for a recall soon.

Thanks

 

They would have to recall most of their fleet. My FJ Cruiser does the same thing.

There are 2 pages in my FJ manual that warn how ABS is NOT meant to shorten stopping distances, and under certain situations can lengthen stopping distances

 

I experienced this on my IV last week. To make a right turn, I started braking just as the front wheels hit a bump on the road. Braking power was not there with the usual pedal pressure. It was like the breaks became very weak. It lasted for about 1/2 second and then it started to brake as usual. I may have increased the pedal pressure to force this. I almost missed the turn. No other incidents since or before. I will try to replicate the event under safe conditions.

 

I have a 2010-V and noticed this problem starting about a month ago. I wondered what it was as it caused me to almost hit a pedestrian....but initially thought it was me. Then, it happened again today. I didn't think anything of it until reading these posts. This is dangerous....has anyone from Toyota indicated when they expect an answer/fix?

 

Re: Floating feeling when braking

[If it matters, I am driving a Prius V.[/QUOTE]

This is a problem Im having w/ my 2010 as well. Im very concerned and mine is in the shop now. I really do think that this will be a recall issue. I just hope too many people wont be in accidents before toyota actually does something. Im filing a report w/ Toyota. Be sure to document it every time.

 

Re: Floating feeling when braking

Hi Kate,

Sorry to hear about:

Can you give us more details:

• locations where the problem occurs - something we can use Google Map to look at the street
• speeds involved when it occurs
• does it happen every time or intermittent

Thanks,
Bob Wilson

 

Re: Floating feeling when braking

Though i have not experienced the floating feeling. i do experience the following sometimes when the car accelerates, it gives you the feeling of being propelled with a feeling of out of control. Also, I have realized that everytime I break the stopping distance is not uniform. Sometimes it makes me skip a heartbeat. But with my previous car i.e. Opel i can predict when i should break hard and soft. I am not an expert but i feel that breaking system is not very impressive.

 

Re: Floating feeling when braking

I have experienced this "floating feeling" especially after the car just rolled over a pot hole but it is not a grave concern for me. However, I found it more concerning is when I am crusing on the highway on cruise control and have to tap on the brake due to slower traffic in the front, the car seems to lung forward at a faster speed when the cruise control is deactivated. This seems to last about half a second. Not that it scares me but the feeling of this design/fault is odd. Anyone else have this feeling?

 

Re: Floating feeling when braking

If you're experiencing floating feeling, I suggest you take a trip to the bathroom pronto!

 

I just made my complaint to NHTSA through its website at [email protected]. I bought a 2010 Prius and I have a cutting brake/sudden acceleration problem with the car when going over rough pavement. It is definitely an issue that needs explanation. I recommend everyone make a complaint. I think the NHTSA will open an investigation if it gets enough complaints. Please do so. It may be a serious safety issue. You owe it to yourself and others!

 

Some of us are trying to understand what is going on. So far:

• Relatively rare - this is by no means a universal problem and seems to have degrees of effect.
• Slow speed - it doesn't seem to happen at high speeds.
• specific surface conditions - in one case, repaving 'cured' the problem, others have found it intermittent at the same location, but we continue to gather helpful pointers from those who have experienced the symptom
  • winter weather is probably making more surfaces capable of triggering the symptom

Thanks to the help from those who have experienced the problem, we have a growing list of surface conditions that seem to trigger the symptom:

http://hiwaay.net/~bzwilson/prius/Prius_bump_010.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_020.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_030.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_040.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_050.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_060.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_070.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_080.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_090.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_100.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_110.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_120.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_130.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_140.jpg
http://hiwaay.net/~bzwilson/prius/Prius_bump_150.jpg
​

You can help by posting photos or Google Street view or Google map addresses of the places this happens. The key to diagnosis will be finding a way to replicate the problem at will. Then we can do things like:

1. swap Prius - if one vehicle always has the problem and another does not, it means finding out what is different between the two
2. quantify the problem - we need engineering units that document time, duration and magnitude

Venting about the problem without specifics such as when and where doesn't help us understand what is going on. Venting with details such as specific locations helps a lot because it moves us closer to understanding what is going on. Is venting going to be part of the problem or part of the solution ... bring us details.

Bob Wilson

 

Acceleration Surge Going Over Bump

When driving locally (<40 mpH) I experience a surge of accelleration when I drive over a bump (such as frost heaves). The dealer can find no problem on computer and has no reports of problem. The accelleration is similar to that which you might get from the a cruse control kicking in, so it has not been dangerous as yet, but causes me to hit the brake. I can find no refernce to this problem on this chat. Has anyone experienced this. Is this normal?

 

Re: Acceleration Surge Going Over Bump

Never heard of anything like that. I suppose it does not happen under braking (because you write that it makes you hit the brake), so it is not the well-known momental loss of braking power. Are you able to reliably reproduce the problem so that you can show it to your dealer, or does it happen only randomly?

 

Re: Acceleration Surge Going Over Bump

RBoyd, there have been recent threads on this. Do a search for "braking" or for "acceleration." The previous threads suggest that acceleration is not occurring, but rather that the brakes briefly do not function after a bump. That often feels like acceleration, but it's not.

 

Re: Acceleration Surge Going Over Bump

Really?