Losing control of the vehicle when the ABS system engages

yes, this is normal behavior. best answer is to slow down. and maybe better tyres

 

Please don't take this the wrong way but on a FWD, you don't hit the brakes when your slipping - you hit the gas. The tire has already lost traction, what is stopping it's rotation going to do for you? On a FWD, most of the weight of the car is over the drive wheel - it only makes sense to regain traction past the slip point. @bisco stated, slow down and plan ahead (aim high, driving metaphor).
I've owned and driven both a VW and Prius C. The VW had a brake booster issue, locked up all 4 tires if I just touched the brake pedal. Dealer took care of that warranty repair. I've notice both car's traction control light flashing when going over potholes on these rough Ca roads. Driven in snow, rain, and over black ice in both cars, traction control behaved as it should. I'm old enough and have enough driving experience that all my previous cars, until I hit 45 years old, didn't even have any computer nannies (traction or stability controls). I've never found them to be intrusive.

If you think you've issue with your traction-, stability-, braking- system, I'd take it to a dealership to get it checked out. Just to be safe.

Now if I can only get the car to stop turning my entire dash board red and displaying BRAKE - I'd be happy. This happens once in a while when I'm approaching a car turning into a driveway too fast. Stupid eyesight pre-collision detection system - that'll wake you up faster than a cup of coffee.

Hopefully this helps.....

 

When was the last time you had a brake inspection?

 

Hmm, for a start you might want to change your driving style to avoid these situations.... /

 

The description as I read it in post #1 does not remind me of any normal Prius behavior at all. I've driven gen 1, gen 2, and gen 3 and in my experience the ABS and VSC do exactly what they say on the tin. The ABS lets me still stop straight and controlled in conditions where I overestimated the traction, and the VSC has kept me under control on curves where I misjudged the speed.

Naturally, neither system can work miracles. A stop where you've overestimated the traction is going to take more distance than you thought. You'll have a longer radius around a curve if the traction breaks. ABS and VSC won't rewrite physics, but they'll do their best so the longer stop is still straight and controlled and the wider curve is still a curve. (If there's a boulder outside that curve, you still might not miss it.)

Of course if you are careful not to misjudge speed or traction, then neither system ever has to activate, and that's the best of all solutions.

There's one known quirk every generation has had that you can notice if you are braking lightly and hit some pavement irregularity like a pothole; it can feel like the car "leaps ahead" a few feet, though it's really more of a brief reduction in slowing while the car shifts from regen to hydraulic braking. It's easily reproducible and you can practice with it to learn just what it's like; it's predictable and minor, and it's over about as soon as you've noticed it. The description above in post #1 sounds very different from that known quirk.

Anything that feels like you "lose control for a [whole!] second", "wouldn't actually stop", "couldn't manually brake", "continued for several [!] seconds", "lost control of the vehicle", etc., could be a real (and not a common) problem. By the same token, having you report such a not-common problem in two consecutive Prii, of different generations, that you have had, hints at a possibility at least that something about your driving could be a common factor. There might be something to say for having another experienced driver do some test driving and see if anything seems weird to them.

Stopping a car that weighs X from speed Y on a wet or snowy road will never happen in less than a certain distance, and if the intersection is closer than that you'll end up in it or through it no matter what. ABS can help make sure you stay pointed the way you're moving and keep some steering control, but it can't stop you shorter than physics dictates.

In a car with ABS, pumping the pedal generally isn't recommended. Pre-ABS, you would do that to give locked wheels a chance to roll again, but ABS does that for you, faster than you can, and per-wheel, which you can't do with one pedal.

 

The one time I experience similar, was with our previous 06 civic hybrid. I'd just had a "professional" brake fluid replacement done. Coupled with that we hadn't had the car for a while (it was with another family member), so I was a little out-of-touch with it's braking feel. One instance: a light went yellow while we were close but should have been able to stop. Went on the brakes, ABS started making noise, and we ended up half-way into the crosswalk.

Anyway, long story short, turned out one of the rear corners was absolutely free-spinning, with the brakes applied. To add insult to injury, about half the bleed screw caps were missing. I took it back; they did it right the second time 'round.

That was Westwood Honda in Port Moody; I always like to give dealerships a plug.