While driving to work this morning at each stop I experienced what felt like a slip and grab. It was like the regenerative braking stopped then the pads grabbed. In between was "Scarytime." I've read about how earler models experienced complete brake failure and am now worried more than before. What do you think?
The friction brakes don't take until slow speed, around 5-7 mph. At higher speeds, it's regenerative braking in use. There is a slight lag between the regenerative braking and the friction braking. That's what you feel and it's normal.
If it makes you feel better, take it to the dealer. You didn't describe the road conditions when you experienced your "Scarytime". Were the roads wet? Had you driven through standing water? How long had you been driving? Was the ICE fully warmed up?
It was a dry cool morning. It happened al the way to work starting when it was cold. It was plenty warm by the time I got there. I'll see what happens as I drive home. Maybe it will change it's mind.
Most likely your brake rotors are a little rusty, which makes for the grabbing feel. Try cleaning them by doing a few stops in N. Tom
My FJ Cruiser will also act up a bit due to the ABS, especially if I happen to be braking and one wheel is over a manhole cover or other surface that is quite different from the normal road surface I very much doubt this was a brake "failure." First of all, the dash would light up like a christmas tree
Wet/cold/slightly rusty. Not to worry. Do a few hard stops and it should go away. If not, then see a dealer.
I've -NEVER- heard of "complete brake failure" in -ANY- model of Prius. I -HAVE- heard of people who managed to get the floor mat under the brake pedal, over the accelerator pedal, etc. This being said, the Prius brakes will make you panic in several ways: 1. As stated above, they switch from "combination regen and friction" to full friction braking at about 11 km/hr or 7 MPH. This results in a "bump" in braking of less than 1/4 sec. If this causes a problem, you are leaving your braking too late!! 2. If you hit a sharp bump while braking the anti-lock will kick in and it will feel as if the brakes failed. Again, if this causes a problem you are leaving your braking too late!! 3. If the roads are wet, icy, or oily the anti-lock will kick in. Again, this can feel as if the brakes failed. They did not. Without anti-lock you may have spun out. And again, if this causes a problem you are leaving your braking too late! Better tires WILL improve braking a lot. The stock tires -any- new car comes with are rim protectors at best. They are often dangerous in marginal conditions. -ESPECIALLY- if under inflated! Check your tires!
Although rare, the occasional Prius brake failure has been reported. This happened to my dad's 2007 with less than 12K miles. The skid control ECU and the brake pedal stroke sensor were replaced. Details here: http://priuschat.com/forums/prius-main-forum/11798-brake-failures-04-prius-6.html
I agree that although rare, this could be the Achilles Heel of the Prius by-wire braking system. Am unsure how the overall failure mode analysis compares to conventional vehicles
