Recall for brakes DID NOT fix the problem

We have a 2010 that apparently hasn't had the brake fix yet - at least I hope to hell it hasn't. The loss of braking may "only" be for most of a second, but that can make a huge difference, even at low speeds. I have a 1995 Civic EX sedan with ABS, and that car, with its "old" technology, stops FAR better than the Prius. Its brakes cycle on and off so rapidly that all you feel is a shudder - no loss of deceleration. And that's how ABS is *supposed to work*. Between the unsafe ABS, the cruise control that won't shut off in regen braking (only when the mechanical brakes are applied) and the traction control that can't be turned off when you need some wheelspin, this car is becoming distinctly unloved in this household. From the little things like buttons that are too small for gloved hands, to the bigger issues above, I can't believe how many mistakes they made with this car. I'm glad we only leased it.

 

Your 1995 Civic does not have regenerative braking so of course the feeling during low speed braking may be different. What you are experiencing is a transition from regenerative braking and ABS. The ABS works perfectly fine in the Prius and is not the reason behind your negative experience. The braking system in my GMC and Chevy trucks created a VERY similar feeling to the Prius braking issue except it was much more dangerous because adding pressure to the brake pedal had zero effect. At least the Prius WILL stop and never once did I feel like I lost control of the car. I have 125,000 miles on my 2005 Prius and I have nary a complaint except for the aggressive traction control which is MUCH more aggressive than that on the 2010. Better tires fixed my problem.

Wheelspin is a different issue and is limited to protect the HSD system. If you are truly having problems due to lack of wheelspin then I suggest trying out a better set of tires. It is kind of like buying a Chevy Z71 truck for use in Alaska then complaining about a lack of traction in the snow. Buy tires specific to your environment. The manufacture tries to match tires to the car for a variety of environments but they don't always get it right so the end user must make adjustments. I didn't chide GM for putting tires on my Trans Am that would disappear in a cloud of smoke when I floored the accelerator. I simply bought better tires that matched my driving style.

I am not trying to downplay your experience. Instead I am giving you explanations and solutions. If that is not enough then I suggest you ditch the car and find something that makes you happy. Life is too short to be unhappy.

 

First, neither the ABS on the Prius or on your trucks is functioning "perfectly fine" - except maybe in both cases they are behaving like normal heavy truck ABS. The problem with the "transition" theory is that it isn't just the long pause before the ABS engages (and that alone is unsafe). It's also how the ABS functions once it's engaged. It cycles on and off at an incredibly leisurely once per 3/4 second or so even after it it's engaged. That is dangerous and ridiculous - ABS only works properly if it cycles many times per second. The car would be substantially safer with no ABS at all. We've gone back to pumping the brakes in snow.

Second, I understand why you might ask about the tires, but you shouldn't assume that I don't know anything about them. We bought the snow tires that came in first in one consumer test and second in another. They behave very well in snow, and are rated 'good to very good' on ice. It's the car causing this problem, not the tires. Manufacturers make mistakes, and Toyota made several with this car.

You can have the last word. I can probably predict what you'll write anyway.

 

I've performed enough panic stops in my Prius to know how well the brakes are working. If you bought a lemon then that is a problem but don't come in here all uppity like you know it all. I have not witnessed, experienced nor heard about problems associated with a lack of braking power due toABS malfunction. If this was truly a big problem there would be a lot of accidents

Yup.

 

I 100% guarantee you there is no way in the world your Prius' cycle rate is once every 3/4 second. You cannot possibly infer its cycle rate simply by feel from the driver's position. The ABS system would definitely be throwing a malfunction code if it was going that slowly.

On a car with ABS? Please stop doing that. If you're going to, at the very least disconnect the ABS fuse, though that's like driving without a seatbelt because in bad accidents they can leave belt marks on one's skin.

 

My experience with Prius ABS is only with the Gen II, so it may be different with the Gen III. With the Gen II, the ABS cycles so fast that you can't even feel it. There is none of the pulsing, thumping, or buzzing commonly found with older ABS. Without the indicator lamp, I wouldn't even know that ABS had kicked in.

Tom

 

My experience with my 2010 is the same as Tom's experience with his 2006. First, you can feel the pulsing in our 2001 Odyssey and it is many times per second and it works, in that it maintains tire rotation, and thus, steering ability. The first time I invoked the ABS on my Prius, I didn't think it was working as there was no pulsing feeling at all. I know it is working as I can stomp on the brakes on ice and still steer, so the tires must be rotating.

 

My wife and I just bought a 2010 III. We have not had any issue with the brakes so far.

 

Sell it. Its clearly going to kill you.

 

The normal pulsing, thumping, etc, are side-effects of the fact that you have another device varying the pressure in the hydraulic circuits. This tends to change the pressure in the master cylinder and therefore kicks the brake pedal around.

The Prius (since Gen II) has fully independent computer control of each wheel cylinder. The master cylinder isn't connected to the wheel cylinders in normal operation. Each wheel cylinder's pressure is varied by two valves, one to increase the pressure (by connecting to a high-pressure accumulator), the other to release it (by connecting to the return pipe to the reservoir). There is no ABS actuator as such: ABS control is done by exactly the same valves, control computer and software as regular service braking. It really shouldn't be a surprise that there is no physical indication of ABS. All that happens is a flashing light on the dash - the buzzer only sounds if VSC activates.

This setup is necessary for brake force distribution, where the braking force on each wheel is individually calculated according to the car's weight distribution and how the tyre is gripping (wheel speed relative to the car's speed). To calculate it properly the tyre pressures should be equal on the same axle. It is also helpful for capturing as much energy as possible with regen braking (as it's not wasting energy through friction braking).

There is a 'fail-safe' mode which connects the master cylinder to the brake pipes if computer control fails. On Gen III this operates all four wheels, but with no ABS, VSC, or brake force distribution. On Gen II it only operates the front wheels and with no power assistance, so any brake system error lights should be investigated immediately.