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
#164 of 370 2007 Toyota Prius with Braking Issue
Feb 09, 2010 (6:07 am)
I own a 2007 Toyota Prius and have experienced occasional momentary loss of braking (my foot firmly on the brake pedal) while driving over a bumpy surface. While braking over small pot holes, railroad tracks, rough patches, etc., the car seems to lunge forward apparently as the brakes release for a split second (approximately 1/4 to 1/2 second). The road conditions can be wet or dry. At the same time, my traction control light will flash on and off until the road smooths out. That split second is enough to cause an accident with the car in front of me if I don't give myself extra room or slow down prior to the bumpy condition (1/2 second at 20 MPH = 15 feet of unwanted travel). I drive over the same railroad tracks just prior to a traffic light every day and I have had to adjust my driving habits to keep this dangerous, additional stopping distance from reoccurring. I have seen similar complaints with earlier models up to the new 2010s on this and other websites. Some believe that this is a software delay that occurs when the braking switches from the electro-magnetic to the mechanical braking system. I would hope Toyota is aware of this (what I consider a design issue) and that earlier models will be included in the recall. So far it's only 2010 models. If you are experiencing the same problem, please contact the National Highway Traffic Safety Administration Vehicle Safety Hotline at 888-327-4236 to make sure Toyota gets the word to include all affected model years. You may also report a safety complaint at: http://www-odi.nhtsa.dot.gov/ivoq/index.cfm
#165 of 370 Toyota Prius braking issues may predate 2010 model; other problems reported
Feb 09, 2010 (11:26 am)
Toyota Prius braking issues may predate 2010 model; other problems reported
Toyota Prius braking issues may predate 2010 model; other problems reported
Could the apparent braking problems reported on the Toyota Prius – which Toyota admits was an issue on the current model prior to being resolved earlier this year – extend past the recently released 2010 model? According to TheDetroitBureau.com, the answer is a resounding... maybe.
The third generation of the popular hybrid hatchback hit the market in 2009 as a 2010 model, and some 300,000 vehicles are thought to have a software glitch that could cause the car to lose braking power for up to one full second under certain circumstances. But that's not all. Apparently, reports of braking issues have been pouring in since 2005 or even earlier. If true, over a million second-generation Prius hybrids could potentially be affected.
Perhaps it's worth mentioning that previous electronic issues have also been reported, such as headlights that burn out too quickly and malfunctioning traction control system. As pointed out by TheDetroitBureau.com, "ABS, traction control, electronic stability control and various other technologies all rely, at least in part, on braking to improve the stopping, handling and stability of today's cars, including Prius."
#166 of 370 Re: 2009 Brake problem [phaters]
Feb 09, 2010 (12:29 pm)
Please see my previous post #81
I took my Prius in and had them look at it on Dec 15th a couple of weeks after I had the accident. They said that everything checked out fine and that it was probably my anti lock brakes kicking in(I moved to Seatlle from Minnesota and I know what anti locke brakes feel like, that wasn't the problem). Since then going down the same hill the car has accelerated when going over a pothole in the road. I called Toyota back and they said that my car is not part of the recall and that when they looked at my car in December they checked the brakes and the accelerator and all checked out! I feel like there is not much else to do. I called them again today and left a message that I want them to take another look. My insurance company said to just keep bugging them. After reading the other posts, the service guys at Toyota must have been told to tell people that they have never heard of this problem! I also feel Toyota should fix the bumper that was dented from the brakes failing to work! URG
#169 of 370 Re: 2009 Brake problem [phaters]
Feb 10, 2010 (7:18 am)
Have you filed a report with the NTSA? They have an online form. I personally believe you as someone who's had the same problem.I think unless people start to complain to the right people, this will be swept under the rug. I encountered the problem one time in my 2007 Prius in December during an ice storm. I live in minnesota and am all to familiar with the feeling of Anti-lock brakes on ice. This was a completely different experience. I had it happen a second time yesterday. I hope it never happens in a busy intersection.
#170 of 370 Re: 2009 Brake problem [phaters]
Feb 10, 2010 (10:11 am)
Hybrid vehicles, unlike ABS implementations in non-hybrid vehicles, have two modes. Mode 1 simply disables regen braking and brings frictional braking online if it is not already. This transition, when frictional braking was not already online, is the cause of the "lurch" or "surge" seat of the pants "sensor" feeling, in reality a brief "lessening" of braking HP.
Once frictional braking comes fully online and if impending wheel lockup detection persists then ABS goes into mode 2 and you get that standard vibratory brake pedal feedback "signal".
In the case of a short bump, pertubation, in the roadbed that causes a brief separation of a driven wheel with the roadbed it is highly likely there will be no cause for ABS to enter mode 2.
#171 of 370 Re: 2010 Prius Owner with Brake issue [tryingedmunds2]
Feb 10, 2010 (1:05 pm)
"...ABS is capable of PWM, Pulse Width Modulation down to 10's of milliseconds is good.."
While electrically/electronically the solenoid voltage can be switched on and off at those rates the mechanical time constants involved only allow a "switch" rate on the order of 100's of milliseconds.
The PWM dutycycle is controlled by the ABS ECU in real-time, and it has two "masters". First, it will not allow the front wheels to slow very much more rapidly than the rear wheels, and vice versa. Second, if it detects that ANY wheel is too rapidly approaching lockup it will instantly release brake fluid pressure on that wheel and will not re-apply pressure until the wheel rotation rate has again risen to some "target" as defined by the current roadspeed.
#172 of 370 2005 Prius Sudden brake problem too
Feb 13, 2010 (9:34 am)
Might as well add my two cents worth here. My 2005 Prius (bought new) acts as if I have slammed on the brakes with only a very light touch on occasion. Mostly mornings. This since the very first year I had it. Toyota of Tampa Bay says they know nothing unless they see the problem. Even just an amateur search on the web shows this is fairly common problem. I filled out the little complaint form at the DOT site of "Office of Defects " and I received back a notice saying if I wanted to file a complain .......call this number.That after already filling out a complaint form. LOL. I notified Toyota but they have yet to give me any indication that this is something they are interested in fixing. It's OK though I have kept records and so if we get in a wreck at least my kids can sue everyone involved and maybe get a few bucks out of the criminals.
#173 of 370 Re: 2005 Prius Sudden brake problem too [phydo]
Feb 13, 2010 (2:46 pm)
Do the brakes WORK; i.e, do they stop the car?