Got into an accident today due to brake problem =(

welp, I experienced this for the first time today as I approached my turnoff from a boulevard (2 months old, 1500+ miles, manufactured in March 2010 so fix should have already been applied). The road is generally rough but there was some particularly broken pavement on the right-hand side that I happened to hit at around 35-40 mph. I had depressed the brake just prior to reaching this section of pavement. In any case, it felt like the car lurched forward for approximately a second (or, at the very least, the braking mechanism released before commencing with deceleration again). I knew exactly what it was when it occurred so I wasn't frightened by it. Just another data point to add to the collection.

 

Thanks!

I think you'll find SSC-A0B will make it 'less exciting.' Certainly I could not replicate the pause after the patch. But you are right, I'm seriously after the post, SSC-A0B incidents.

Thanks,
Bob Wilson

 

Can you get a photo of the 'broken pavement?' Is it something that was badly patched? Are there loose chunks? Estimated length?

When you get your car into the shop, please ask them to read out and give you a printing of the brake software version.

Thanks,
Bob Wilson

 

Bob,

My 2010 Prius experiences the momentary loss of braking at the following places, consistently, on my daily commute to work.

[ame="http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=bowman+road+and+brodie+creek+trail&sll=37.0625,-95.677068&sspn=30.599615,85.078125&ie=UTF8&hq=&hnear=Bowman+Rd+%26+Brodie+Creek+Trail,+Little+Rock,+Pulaski,+Arkansas+72211&ll=34.729611,-92.409082&spn=0.000977,0.003618&t=h&z=19&layer=c&cbll=34.729664,-92.409172&panoid=nWFdJMfUE46eRqIeu_nxaA&cbp=12,313.37,,0,1.86"]bowman road and brodie creek trail - Google Maps[/ame]

The above shows a raised brick walkway (1' or 2" speed bump?) at the exit of my neighborhood. Usually happens here if I am above 7mph. If were to only be driving 7mph at this point, any cars behind me would not be happy. Most cars would have just started braking from 25mph just prior to this brick area.

[ame="http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=I-630+exit+2a&sll=34.735794,-92.400942&sspn=0.014601,0.041542&ie=UTF8&hq=I-630+exit+2a&hnear=&ll=34.733135,-92.258991&spn=0,0.003618&t=h&z=19&layer=c&cbll=34.733094,-92.258869&panoid=mY6j_tEOfp-j3dw8Nrn8Ug&cbp=12,105.49,,0,10.4"]I-630 exit 2a - Google Maps[/ame]

The above shows an intersection with a 4-way stop sign at the end of an off-ramp on I-630. The pavement is very uneven with inconsistent ripples in the pavement on the left and right side of the car. My 2010 Prius consistently experiences the momentary loss of braking here.

[ame="http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=I-630+exit+2a&sll=34.735794,-92.400942&sspn=0.014601,0.041542&ie=UTF8&hq=I-630+exit+2a&hnear=&ll=34.732765,-92.254807&spn=0,0.003618&t=h&z=19&layer=c&cbll=34.73281,-92.254866&panoid=uUaANsP0iEGSFxgea5m4RQ&cbp=12,124.47,,0,6.27"]I-630 exit 2a - Google Maps[/ame]

The above shows extremely uneven railroad tracks crossing 15th street. Entering the area of uneven pavement just prior to the tracks at 8mph or faster under braking causes the momentary loss of braking. This is easily avoided here by braking firmly just prior to bumpy pavement and releasing brakes while crossing tracks. However, it occasionally happens when vehicles ahead slow unexpectedly on the other side of the tracks and I must brake over bumpy area and I am above 7mph.

[ame="http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=I-630+exit+2a&sll=34.735794,-92.400942&sspn=0.014601,0.041542&ie=UTF8&hq=I-630+exit+2a&hnear=&ll=34.732355,-92.250376&spn=0,0.003618&t=h&z=19&layer=c&cbll=34.732352,-92.250269&panoid=HZeOexq7E-jVlDP6fQcR7w&cbp=12,92.92,,0,7.4"]I-630 exit 2a - Google Maps[/ame]

The above is the most disconcerting of all areas on my daily commute. This area is horribly bumpy with extremely uneven ripples in the pavement due to the amount of trucks using this road from the beer distributor nearby. While braking for the 90 degree right-hand turn on this stretch of road, I not only feel the momentary loss of braking, but the brake pedal drastically changes it's feel in firmness or pressure. It is very difficult to describe, but the amount of braking force changes rapidly in response to the amount of pressure applied to the pedal in an ever changing battle. On occasion, I have actually moved the shifter into neutral here until I am around this corner to avoid the sensation. When I do this, the Prius brakes evenly and consistently. The instant the car shifts into neutral, all of the strange pedal pressure inconsistency goes away and it brakes very well.

[ame="http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=I-630+exit+2a&sll=34.735794,-92.400942&sspn=0.014601,0.041542&ie=UTF8&hq=I-630+exit+2a&hnear=&ll=34.730433,-92.245655&spn=0,0.003618&t=h&z=19&layer=c&cbll=34.730434,-92.245556&panoid=YRIoqplwSykrvLMhREUYdQ&cbp=12,102.1,,0,5.6"]I-630 exit 2a - Google Maps[/ame]

The above is an area of pavement leading up to and crossing more railroad tracks that is horribly uneven. Braking here at anything above 7mph causes the momentary loss of braking. Not that big of deal here since the pavement is SO uneven, I would not want to enter this area above that speed anyway. If you do not ensure the car reaches 7mph before the rippled pavement, it feels like the Prius "slides" onto the tracks before hydraulic braking takes over.

Again, I am not saying that any of these will cause an accident. I am just saying that I feel this momentary loss of braking force at these spots almost everyday during my commute to work. I have been driving a 2010 Camry loaner car since last Tuesday and have not felt the same sensation at any of these locations. In my opinion, the recall did not change the braking characteristics of my 2010 Prius at all.

Thanks,

Troy

 

brad_rules_man,

Really? I should drive my Prius in a manner that ensures I am below 8mph before I drive across any pavement that may or may not be uneven or have a manhole cover in my path? I am sure you would just love to be behind me in your BMW if we all drove our Hybrids like that.

 

I've only driven my new Prius about 1400 miles, but still haven't really been able to create this problem yet. I did feel a very subtle "loss of deceleration" yesterday that made me think it might have been the beginning of the "problem." It occurred while decel'ing using mostly regen. and the road did one of those quick undulating up and down motions from where the pavement had a slight wave in it, and, just for a split second, I might have felt something. I actually WANT to be able to duplicate this, just so I can experience it and be on guard, should it ever take me by surprise.
I've read every thread I could find about this, and, from what I can glean, this is happening mainly when people are braking lightly, in other words, using regen. As part of the driving technique I'm developing, I try to regen brake whenever I can, to build battery up and save the brake pads. One thing I've noticed is that there is very little feedback in terms of pedal feel for the regen braking effect. Passengers in the car sometimes think I'm about to rear end a car because I'm scrubbing speed off fairly slowly, trying to keep the brake system in regen. I've never had an instance, even over uneven pavement, when I couldn't just push harder and get virtually instant HARD braking, so I tend to push the limits of regen a bit, trying to maximize efficiency. So, several times I've been coming up on a stopping point, and, having the confidence that the system will work when I really need it, have just kept the pedal pressure constant and "let the regen stop the car." It's a little bit scary, as I don't really feel the car stopping, but it really slows down those last 25 feet or so, under regen. With normal brakes, you'd have to push the pedal harder - anyway, maybe you get the idea I'm trying to convey here.
Now, if I were driving using this braking technique, and I cut it a bit too close, AND there was road surface unevenness I didn't plan for that caused the regen effect to quickly end, I could have a problem if I either didn't get back on the pedal quickly, or if the system had a "delay" before implementing my hard brake command. What I'm wondering, for those who've experienced a problem, is: is there a discernible gap between applying that extra brake pressure and the car implementing the driver input that is not attributable to normal ABS action? I add that last bit because I'm already pretty familiar with ABS delay, and got over being scared by that years ago - it's "normal," but if there is a hybrid-system particular delay that's happening, I want to experience it and be prepared.
I do tend to brake extra-conservatively in the Prius - but will continue to seek out situations that are anomalous to try to be prepared.

 

Thank you Troy!

These are some of the best documented locations seen yet! Now I have an idea of several places where I should be able to find similar, railroad crossings. The 'brick speed bump' is also interesting.

Now I'm really interested in the version of your ABS software. You have all of the classic symptoms of the 'brake pause.' But there may be another, previously undiagnosed fault, occurring. I'll try to replicate although the brick speed bump is unlikely.

Bob Wilson

 

Bob, you seem to think every single case may have another, previously undiagnosed fault occurring. Why is this?

 

I'm reminded of the old joke about the tombstone with the words:

I told you I was sick!
​

I prefer to diagnose a problem after getting the facts and data. Often, getting the symptoms adds 'enlightenment' to all parties and does no harm. This latest one from Arkansas is especially interesting because it has added road surfaces not previously seen. Of course, I could have Alzheimer's. <GRINS>

Bob Wilson

 

Haven't had the problem but to criticize a poster because they are NooB and "low post counts "
seems unwelcoming ...

Well excuse ME" What better way for a New owner looking for answers and finding a great site here @ PC...

What do you want them to do, wait to post a Question or add their anecdotal experience?:focus:

 

I agree completely. Had the same problem....

 

Sure, I could do all of those things. Yes, it was a bad patch IIRC and the length was perhaps 3 feet? It would be best if I get a photo, which I will do when I'm back in the area in a week. Google maps photography is shot from the far side of the boulevard unfortunately.

EDIT: I spoke too soon. Upon further inspection, I think this hole/patchy area is the one that resulted in the momentary ceasing of braking:

[ame="http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=forest+and+high+dale&sll=37.0625,-95.677068&sspn=49.844639,67.675781&ie=UTF8&hq=&hnear=Forest+Ln+%26+High+Dale+Dr,+Dallas,+Texas+75234&t=h&layer=c&cbll=32.9097,-96.860654&panoid=r2Q1Dvahdb2R8rCjUmejnQ&cbp=12,273.71,,0,34.71&ll=32.909705,-96.860796&spn=0.000813,0.001033&z=20"]forest and high dale - Google Maps[/ame]

If that is up to date, it appears there are actually 2 broken patchy areas that may have contributed to it. I'll have to go back to the area and compare with a new photo.

 

Wow! That looks a lot like some of the first patches:




These are some of the first problem areas fixed by SSC-A0B. Curious, you're getting similar symptoms.

Bob Wilson

 

Good catch and very curious indeed...it would mean it isn't 100% resolved, or my vehicle hasn't received the fix (which would have been a pretty serious Toyota oversight as mine was manuf'd in March).

 

I noticed the braking problem on my 2010 Prius the first week I got it. After the upgrade, it did seem like the braking got better. But I still notice when braking gradually and then you hit a bumpy patch, sometimes the brakes (regenerative braking) let go and you have to immediately press harder to brake enough.

 

No, but if your on an uneven surface and slowing down for a stop sign, you probably should be at 8mph that distance from it. Also, if this condition engages and your only going 8mph, are you seriously covering enough distance in those few fractions of a second where it is an issue? Or does it just startle you and make you feel uneasy? And if your going faster, which you would be at other circumstances, just leave enough of a buffer between you and the next car, or whatever your next obstacle would be. I experience this occasionally by surprise, and then there are a few areas that (like you) I know there is an issue. Then I obviously adapt.

I don't drive a BMW anymore, but yes when downshifting you have to be ready for uneven surfaces. I simply suggest you learn how to drive your car instead of trying to argue about non-issues.

I don't know if you noticed but Toyota was trying to suck up to us all and say they knew about the problem because so many new owners reported it, having not driven cars with drivetrain braking ever, or for a long time. So, they pandered to everyone and released this "update" which did very little and didn't address the issue because there really isn't a way to address it.

I think they need call everyone in for a recall, and sit them down in front of an information/training video explaining how the car acts, and how to adapt to them. I'm not saying that anyone is dumb, or wrong. I'm just saying people have really been spoiled by modern cars and automatic transmissions. It's a wonderful luxury, but to cross into an efficient realm, it's likely going to take sacrifices on many ends.. money, and convenience.

And yes, I reiterate that I have experienced the condition, but it has NEVER been dangerous because I am a very good and defensive driver. I allow a 3-4 second buffer minimum. One of three conditions would have to be met for me to experience an accident: an invasion into my space by another driver, an error in my driving, or the braking condition. Any one of these things happen, and I am going to be fine. Any combination of any two of these things happen and I am most likely going to have an accident. It's just safe driving, every state's rules of the road book states that it is your responsibility to earn and maintain the privilege of driving a motor vehicle. Every state says that it's always up to you to drive defensively and leave room for others errors, or conditions that you cannot control.

Coming from a BMW 330i with a manual into a Prius,... and experiencing this situation.. it's sort of laughable compared to loosing your traction while downshifting. The milliseconds that it takes to engage the friction brakes are WAY less than when downshifting.

 

The momentary lost of braking force when transition from regen to friction braking and when the VSC kicks in over rough surface is a "CHARACTERISTIC" of the Prius braking system, so there isn't anything wrong with it. From a marketing perspective, it is just a design feature.

 

I'm going to chime in and just point out (again again again) i've had the car since the more real 'issue (I place the issue word more as a joke - but know it was very real)'. Before it was a bit scary (yes as a guy I say this - not to diminish any female perspective). Now it is harmless and I accept the system works quite well - in fact - as more a naysayer previously, I can state it really works well. I accept there is a slight 'loss' feeling, but the car stops fast. I've used that fast a few times.
'
There is no need to "learn how to drive/brake" - it just works. I am no random poster - I have miles and miles of experience (20K?) - and am on my second car - the previous one flipping at 45mph - with 4 (14 to 10 yrs old) kids en tow. 8 airbags went off. The car was totaled (insurance), I got my hand burned by the airbag - otherwise, everyone was 100% (not a bad burn - but as the sole injured person on an 8 airbag total where if you looked at the car you would think people were dead - not bad)

Would I think to replace *that* with anything but - no. Brakes had nothing to do with the accident - I was distracted by the yelling in the back.

Enough rant - enjoy your car - it is likely safer than most other cars...

{For those who will wonder what happened, I was distracted - looked behind, we drifted left into a center median - concrete horseshoe type thing - no traffic - it was raining - but that did not matter - car is very low - we hit the curb straight on - it 'hooked' the bottom and we went end over (head over heels), then rolled at around 45. We were upside down, and I had to undo passenger seat belt etc. To think that no one had injuries defies me}

Please don't post more on what I {accident} had - I know we are lucky, and appreciate anything you may post. Let's keep it on topic - but appreciate what we drive....

 

Paul,

The original post did not indicate that he used the emergency foot brake. That is the pedal to the left of the main brake (hand brake in some cars) You may not have noticed because you are too busy making idiotic comments. That brake has a MECHANICAL LINKAGE TO THE REAR BRAKES. This system is INDEPENDENT of any electrical malfunctions that any of these "unintended acceleration/brake failure" proponents are alleging.

You may also want to look up sarcasm in the dictionary. The comment about stopping the car with your shoe was a joke. But your are too busy being a scholar to notice.

You are apparently in your own mind very well read and are an expert in all areas. I encourage you to look in the mirror and see what an idiot you are.

 

-- accidental post --