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
Go to NHTSA to file a safety complaint.
Or call Monday-Friday (8 am to 8 pm ET) (888) 327-4236 TTY: (800)424-9153
#126 of 370 2009 Prius brake problems
Feb 04, 2010 (11:38 am)
I just found this forum, too. I thought I was alone.
On the morning of June 9, 2009 I was traveling South on I-93 near the town of Medford, MA. I was on my way to Logan Airport to return the 2009 Toyota Prius I had rented that previous Wednesday. It was approximately 9:30 AM; the freeway was still bumper-to-bumper with rush hour traffic. I was in the left-hand lane of the highway and traffic was stop and go.
A gap opened up in traffic and I accelerated. The car in front of me (approximately 60’ ahead) suddenly stopped. I slammed on the brakes but my car kept going. There was nothing I could do as my car plowed into the car in front of me, at the speed of approximately 10 mph. The impact was sufficient to dislodge my license plate. There was no apparent damage to the car in front of me, however the two passengers were extremely shaken up.
There was a Massachusetts state trooper on the scene who took all the information but did not file a report. As soon as I could, at about 11:00 AM, I called my insurance company, USAA to report the accident, and I explained all of the details to them.
It is unfortunate that these problems are just now getting attention. Think about how many accidents could have been avoided if this issue had been brought to light sooner.
#127 of 370 Re: 2010 Prius Owner with Brake issue [steveindenver]
Feb 04, 2010 (12:33 pm)
In some sense what you are describing is SOP, Standard Operating Procedure.
With these hybrids when you apply the brakes the system is biased toward the use of regen braking, more HEAVILY biased the lower the hybrid battery charge level happens to be.
So, you're braking moderately, using regen braking only, in order to come to a reasonably gentle stop. Then for whatever reason (pothole, railway rail, plastic crosswalk stripping, wet/oil spot, etc) ABS detects impending wheel lockup and instantly DISABLES regen braking in favor of frictional braking only.
Note: In many cases you may never know ABS has "activated".
Now, for a brief moment you might feel a "surge" forward due to the transition period between the time of disabling the regen braking and the frictional brake pads coming into contact with the brake rotors hard enough to reach the same level of braking you had just previously.
Even worse if the street is oil and rain slicked ABS will kick and you you might well feel that as brakes grabbing. It is not at all unusual for ABS activation to result in elongating your braking distance in a fairly slippery surface by an extraordinary measure.
#128 of 370 Re: 2010 Prius Owner with Brake issue [wwest]
Feb 04, 2010 (1:05 pm)
So, if I am understanding you correctly, you are saying that if you want to be able to stop reliably on uneven or somewhat slippery surfaces, you better drive something other than a Prius.
Since I do not drive a Prius, I will from now on turn on my hazards when it is raining and there is a Prius behind me.
#129 of 370 2006 Prius Braking problem
Feb 04, 2010 (1:09 pm)
I have a 2006 Prius. I noticed the issue of the car surging forward momentarily when a pothole or a bump is hit (and the VSA light comes on). Like many others, I thought this was normal and just ignored it. But apparently now Toyota has recognized this as a problem, but only for the 2010 model. I went ahead and filed a complaint on NHTSA's website. I urge others to do the same, so we can get our non-2010 models fixed as well.
Another problem I noticed is that when the road is wet, and if I was at a complete stop and tried to accelerate too fast, the car will actually kind of "slip"--it doesn't accelerate as intended but actually stalls momentarily. The way to overcome this problem is to step on the gas pedal very lightly. So with slow acceleration, everything is fine, but if you tried to rush it, it won't work. This is a severe disadvantage if you are sitting at a busy intersection trying to make a turn, because you want to go fast to avoid be hit, but like I said, trying to go faster will actually backfire.
Has anyone else noticed this?
#130 of 370 Scary stuff.
Feb 04, 2010 (1:35 pm)
The main Toyota brake pedal problem is mechanical and that I can understand.
However it is a whole new ballgame when computers start playing up.
I just think of this thing in front of me and the problems I have, with a need to power cycle the thing every month or so. You cannot do that travelling at 70mph.
Better the old days when brakes were a mechanical function you always seemed to have warning when things were not right.
#131 of 370 Re: 2006 Prius Braking problem [ericqli]
Feb 04, 2010 (1:51 pm)
I have had the same problem in my 2008 Prius. I just figured it was how the Prius worked, I didn't realize it was a problem. But I will definitely be filing a complaint now.
#132 of 370 Re: 2006 Prius Braking problem [ericqli]
Feb 04, 2010 (2:59 pm)
"..Has anyone noticed this?.."
That's called TC, Traction Control. If you try to use too much engine torque for roadbed conditions the drive, driven, wheels will tend to slip. When that happens TC will activate and instantly reduce the drive power from the HSD system. Most of the time it will also apply braking to the slipping wheels.
With a FWD or F/awd vehicle wheelslip/spin of the drive/driven wheels is of such seriously hazardous nature, HIGH potential for subsequent loss of directional control, that the TC reaction to the must be INSTANT, full and complete.
If you happen to also be turning as you accelerate the TC (more likely VSC)functionality will likely be even more firm and sudden.
Keep in mind that for its weight the Prius has an unusual level of get up and go from a full stop. Low speed torque derived from those synchronous AC motors.
#133 of 370 Re: 2010 Prius Owner with Brake issue [buyamerican2]
Feb 04, 2010 (3:04 pm)
"..you better drive something other than a Prius.."
No, not saying that at all.
What I am saying is that if you drive any of the current crop of hybrids that use regen braking you should be prepared for that seat of the pants "feel" of a momentary, millisecond, forward surge. In most cases that momentary "lurch" in brake application will have no detrimental effect.
#134 of 370 Re: 2010 Prius [doobs1]
Feb 04, 2010 (3:16 pm)
I'm in exactly the same boat....supposed to pick up mine Friday....if you get any tips, please let me know....I'm in Canada....how about you?