I drive a 2010 Prius which I bought in July 2010. After having had to hit the brakes full throttle to avoid a collision I now have the following issue. Every so often when coming up to a red light and starting to brake in a normal fashion, all of a sudden the brake power just disappears and the car no longer brakes as it should. I then release and hit the brake again and the car luckily comes to a stop before I hit the car in front of me. I have had this happen twice and two days now. Went to the dealer who told me he checked the computer and there is no error code. Somehow sounds like the issue that supposedly was fixed in the beginning of 2010 with a software update. Has anyone else had this happen? My dealer says there is nothing wrong but then he hasn't driven the car and experienced this.
The tech did drive it. Unfortunately it only happens once in a while and they did not experience the issue. I can not replicate it unfortunately. They told me that basically I am the only one that has reported this issue which I seriously doubt.
This happens almost all the time time whenever the car goes over a bump while slowing down. Got the same BS you did from the dealer and Toyota Corp. Suggest that you report it to Consumer Reports and the NHTSA https://www-odi.nhtsa.dot.gov/ivoq/ . With enough complaints, maybe Toyota will be forced to finally repair the problem.
Did already report it to the NHTSA. Good idea with Consumer Reports. I did not notice a bump the last time it happened but will keep this in mind. Thanks.
and it never happened before you were flooring the throttle and had to slam the brakes on to avoid a collision?
I have not had mine to the dealer for recall yet,Just lazy I guess! I think it's a lag time between the regen brakes and the normal (disc)brakes, I think the update shortens that time! some experts here know better then I do,let me know if I'm wrong! It's scary as h$ll when you don't know it's coming! HowStuffWorks "Regenerative Braking Diagram"
I assume you had the recall performed on your Prius. I would continue to take it to your dealer (or try another dealer) so that you have a record of multiple complaints. Also, contact your Toyota regional service manager and Toyota Customer Service. In the meantime, allow enough room between you and the car in front. That's a lousy solution, but what can you do until it's repaired!
Ooops, forgot to add: With conventional brakes, having to pump the brakes to build up pressure is an indicator of a failed or leaking master brake cylinder, but I don't that's the issue with a Prius. Sorry, I have more blah, blah, blah, then helpful information.
Did your emergency stop cause any noticeable damage or wear to the tires or brakes? Also, what happens if you step harder on the brake when you notice the problem, rather than releasing the pedal?
If this brake glitch happens at low speed below about 7 mph without any road roughness, it may be that your panic stop damaged a defective brake master cylinder seal. That's uncommon but the hydraulic brake master cylinder doesn't get used much. It may go away or get worse.
The software update doesn't eliminate the perceived acceleration during the regenerative to friction braking transition entirely but shortens it to the Gen II's level. Completely normal and it'll only happen when braking over some road imperfection. People who insist it's not normal ought to go back to a car with conventional brakes.
I had the same thing happen to me. I'm fairly new to the Hybrid world considering this is my first Prius and its only been a year. But I wouldn't worry too much. It seems to happen on bumps and imperfections in the road. It reminds me of conventional brakes, when you hit the brakes and your wheels touch a bump/imperfection/uneven surface it would sometimes go into ABS mode. I guess keep an eye on it but don't be quick to think the worst. That's how things got crazy during the last fiasco.People panicked and the Media had a ball with it.
Its also worth mentioning there's no need to release and reapply the brake, just push a little harder and full braking force is still available. It does feel weird the first couple of times, but you get used to it.
This is very simple. If it happened at slow speed on smooth surface, it's a master cylinder problem. If not it's the same old brake feel.
