Last post on Sep 03, 2013 at 5:22 PM
You are in the Toyota Prius
What is this discussion about?
Toyota Prius, Brakes, Hatchback, Sedan
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#324 of 370 Re: My 2010 Prius still surges after fix. [stevegold]
Jun 15, 2010 (2:31 pm)
The 2010 Prius had a serious firmware design flaw wherein the ABS would "signal" the regenerative braking system that since wheelslip had been detected only frictional braking could, was to be, used. The problem was that somewhere in the back and forth communications between the two ECU's a disconnect occured and although regenerative braking would be discontinued accordingly frictional braking would sometimes be delayed, sometimes indefinitely, coming online.
Not just a slight lurch but seconds or more of virtually no braking effort.
Scary moments resulted.
Once you have endured a few of those moments even any little bit of brake "fade", "slight surge", common to the Prius, becomes a heart in throat event.
#325 of 370 2010 Prius IV with NAV
Jun 15, 2010 (5:41 pm)
Not a single issue after over 1000 miles in ODO and I am enjoying every bit of the smooth and safe driving of this real cutie... 2nd tank with over 610 miles and 68.5MPG computer calculated... wow, what an awesome vehicle Toyota has built...
#326 of 370 Re: My 2010 Prius still surges after fix. [wwest]
Jun 15, 2010 (7:27 pm)
>> Not just a slight lurch but seconds or more of virtually no braking effort
#327 of 370 Re: My 2010 Prius still surges after fix. [john1701a]
by PFFlyer@Edmunds HOST
Jun 16, 2010 (3:06 am)
700 milliseconds IS significant if you ask me. At at just 20 mph, a speed you might be going in close proximity to a car in from of you, that 7/10ths of a second translates to 20 feet before a car would begin to stop.
#328 of 370 Re: My 2010 Prius still surges after fix. [john1701a]
Jun 16, 2010 (8:10 am)
Where did you get this number/limit...?
My understanding is that the non-braking time is random, possibly infinite, due to a design flaw within the firmware.
But yes, even 100 milliseconds of absolutely no braking can not only be extremely frightening but easily result in an accident. In the past ten or more years I have been involved in two "light" rear enders due to needless ABS activation that inadvertently extended my stopping distance on a perfectly dry highly tractive surface.
In my opinion ABS should NEVER activate unless VSC indicates a need for stearage, either the vehicle is not following the driver's stearing inputs, plowing, or is over-stearing.
#329 of 370 Re: My 2010 Prius still surges after fix. [wwest]
by PFFlyer@Edmunds HOST
Jun 16, 2010 (5:35 pm)
We just bought our first vehicle that came with ABS standard. Only about 1,500 miles so far so I haven't run into any situations where I've noticed any difference yet. Hopefully I never will
#330 of 370 Re: My 2010 Prius still surges after fix. [pf_flyer]
Jun 16, 2010 (7:04 pm)
You'd have to be braking fairly hard only using regen, strike a large pothole, and be approaching a vehicle already at a dead stop 20 feet from there. Could happen. Highly unlikely though. And probably never after getting the update.
#331 of 370 Re: My 2010 Prius still surges after fix. [john1701a]
Jun 17, 2010 (6:33 am)
"...You'd have to be braking fairly hard only using regen..."
No, the lurch/surge occurs as the result of the need to transition to ONLY frictional braking from LIGHT regen braking or (typically) heavier combined regen/frictional braking. ABS is ONLY implemented on the frictional brakes.
No, any small perturbation or slippery spot in the roadbed that results in a regen braking tire's loss of contact/traction, even momentarily. Loss of traction sampling, calculation, is done, typically, every 10 milliseconds, 100 times/second.
"..Highly unlikely though..."
Actually, more likely than otherwise if you drive any hybrid on a regular basis.
"..and probably never after getting the update..."
Wrong. The lurch/surge forward is systemic to ALL Toyota HSD hybrid vehicles and cross-licensed "clones". The service campaign only addresses the firmware flaw that tended to elongate the low or even non-braking time during this ABS induced transition period.
#332 of 370 Re: My 2010 Prius still surges after fix. [pf_flyer]
Jun 17, 2010 (6:38 am)
The first ABS equipped vehicle we owned was a 92 Jeep Cherokee Limited. I always removed the ABS pumpmotor fuse during the summer months when loss of stearage control due to heavy braking was less likely to occur.
Unless you need to input directional control or corrections during the "event" all ABS activation does is elongate your stopping distance.
#333 of 370 Re: My 2010 Prius still surges after fix. [betsyr]
Aug 03, 2010 (11:28 am)
While I can't tell you to drive and enjoy your car, I can say that my 2010 Prius is a dream. I've experienced a slight breaking delay when going thru a pothole or over a severe bump. I keep my foot on the break and after a second or two the delay is over.
When I got the car, I was concerned about this and just stayed far enough away from the car in front of me so I would feel comfortable. Now, I don't even do that as I've gotten used to the slight delay and am not really concerned.