2010 brake system

I don't understand the lack of additional X deceleration on hitting the speed bump. When the wheels hit the bump, there should be an additional force component in the -X axis. Instead, the graph seems (eyeballing in lieu of a best curve fit) to indicate the opposite.

 

Bob, NICE JOB, I am impressed with diligence, you shuuld hold a presser since Toyota has not and explain whats going on!!!!

 

According to an AP story this morning:

"The Toyota executive overseeing quality Shinichi Sasaki said the delay that Prius drivers can feel when braking lasts for a fraction of a second as the antilock brakes kick in.

The problem happens only on snowy or bumpy surfaces, and the complaints did not become more numerous until recently when the weather got colder, Sasaki said. "

I've followed the PC discussion for a few months and haven't seen much on problems due to cold / slippery conditions or the antilock system.

Can anyone help resolve the apparent discrepancy?

 

Ice and snow can certainly cause the regen/ABS transition that is at the core of the braking issue. Perhaps the reason that you don't hear about it much on PC is that most of us accustomed to driving in winter conditions are also accustomed to loss of traction and braking. Winter driving isn't for sissies. Regardless of what type of car or truck you drive, if you drive in winter conditions you expect braking and control problems.

Tom

 

Great work Bob.
I have been thinking about why the time (almost 1 sec) and distance your charts show lost braking might be so much longer than I recall in my 2 incidents and why peoples' reports and impressions vary so much.
My impression is that most individuals sense fairly consistent behavior.
One possibility is that individual cars are different.
Another might be that different people might sense and control braking differently.
I believe that your charts were based on constant brake pedal position.
It would be very interesting to see what it looks like with constant pedal pressure.
My guess is that both time and distance would be substantially less.

 

Good idea! I'll bet if slippery conditions caused the regen/ABS transition, I'd never notice a brief delay in friction braking. I'd just assume lack of traction was at fault.

I have experienced the bump-induced brake delay (very rarely), without any indication of ABS involvement. That’s why I wondered why Toyota was emphasizing delay in the antilock system.

 

Winter driving responses are the other half of what saved me from a long-ago Sudden Unintended Acceleration, really a fatigue-induced pedal misapplication. Despite the fatigue, and being in the middle of summer, the right foot reflex responded as if the 'failed' brakes were locked on slick roads, and moved to unlock them. (no ABS in that car.) Incident terminated.

 

A very brief skid (for me, 1 foot on a wet pedestrian crosswalk line) or
a "sufficient" bump apparently triggers the skid-sensor, which results
in the regen braking being turned off for about a second.

Even if one is FAST, it takes about a half second to realize what is happening,
and another half second to figure out what to do about it.
By then, you might have gotten too close to avoid a crash.

And, for most of us, the first time it happens, we are just NOT that fast.
Persons not knowing about it at all ... will likely be slower yet.

So, the "fix" that Toyota has been putting in new-manufacture cars for about
a month, is now available to the rest of us.

Thanks, Toyota!
I got it "installed" today.

 

While the SGII is slow to update and might not be hugely useful here, I added 3 new XGAUGEs to my spreadsheet tonight:

- Regen Cooperation: On or Off depending if Regen braking is actually happening or not
- Regen Requested: Shows in NM what the Skid ECU is asking for Regen wise
- Regen Operation: Shows in NM what the Hybrid ECU is actually delivering in regen braking


https://spreadsheets.google.com/ccc?key=0AiHL0r_2nhUEdF9lVVBxOVNoN3Zva3E0NmdZTUR1eVE&hl=en

Could be useful to see if regen really kicks off at the slightest hint of ABS activation, etc etc.

 

Hi - Are these documents :"New Car Features" publicly available? I've done a Google search, and the only result is this very thread.

I think they'd be interesting to review.

Thanks,
Eric

 

What a pompous a-hole you are. Strike one, right?

 

PLOINK you and the Prius you rode in on. Strike two, right? Go ahead, get even.

 

I'm trying to figure out what's going on here.

You have the first two posts in a thread that had not seen any activity for two and one-half years. My hope is that you were looking to read up on braking anomalies in the 2010 Prius. If so, I'd also hope you would be engaging in some sort of positive discussion, like you have in the past.

If you have some other objective or a particular beef with Bob Wilson, then say it straight out.

 

Under 10 mph it hit a big speed bump. Within minutes I noticed a rumble and vibration very similar to the grooves to slow cars at tolls or when they machine the road to re-surface. The progression of symptoms was fast. Within days ( because the rumble) I time I noticed more transitioning between and shorter intervals. Noticeable increase in gas consumption and hv battery variations. I have new tires and just got oem dealer installed traction battery and alignment. Naw there are what sounds like if the heat shield was dragging. I believe reading you thread I am home. Just to add it is an 06 Prius gen II WITH 158,000. No warning lights or leaks. Good temp, fluids, air pressure. The suddenness and progression of additional and worsened from the bump to now, 5 days and I am a low mileage easy on the petal retired guy. I’m only inquiring so I might speak with a degree of understanding in order to talk to the service writer and not have him say. “Ok” let’s start over….. “.