I think you might not be noticing it because it's very subtle. I only noticed it (changing from regenerative braking to friction braking) the other day after owning the car for 5 months.
It's not that much of a change and certainly nothing worth worrying about.
As long as the car stops, you should be okay.
If it doesn't stop, then you got something to worry about.

 

You've just discovered Pulse and Glide! Removing your foot from the accell pedal will immediately activate regen braking...not alot, but some. Then if you gently (I mean, VERY gently) depress the brake pedal, you will be in the coast mode or glide or whatever you may call it when no arrows are showing on the screen. Do all Cam Hybrids have the screen that shows the energy flowing from/to the various hybrid parts? Sorry if you don't have the screen, this explanation will be slighly less helpful. Anyway in this mode there is no regen drag to slow you, nor any motive force from the electric motorto move you forward...and you speed up if you are on a slight decline (or even on flat roads).

This is the most efficient part of HSD, as it truly is a "let momemtum and gravity keep you moving" mode.

That accell pedal is the controller for all this. Different positions during certain conditions will seem like the car lurched forward when in fact you (with the car's computers helping) put the car into the glide mode when none of the drive train is engaged...soap-box derby mode!

Curt

 

I can't say that I've noticed this "problem." The cruise control is supposed to disengage as soon as the stop-light switch is activated. This should take only a few millimeters of pedal travel. (At night you can check this by looking in your rear-view mirror. You can see the reflection of the high-mount stop-light LEDs on the rear window glass.) Mine does this. If yours doesn't behave this way, a warranty adjustment may be in order.

Stan

P.S. I've just seen finman's post. I think he's got part of the explanation! When you disengage cruise control by using a tap on the brake pedal, since your foot is off the accelerator pedal, the car will begin coasting under mild regenerative braking, which will cause a small deceleration lurch. You can control the extent of the lurch, and whether it's forwards or backwards, by first feathering the accelerator pedal (2-footed driving); or better (1-footed) by using the steering-wheel lever to disengage the cruise control, after first feathering the accelerator.

 

I had this happen again yesterday and sure enough it was as I hit a small bump in the road while applying the brake. This spring there are a lot of 'bumps' in the road here in the upper midwest due to the nasty winter this year so that is likely why I'm experiencing this more frequently than most. This isn't dangerous, the car brakes, just a weird 'feeling'.

 

Yes, it can be very subtle at times. Sometimes I only notice it by sound alone; the regen whine suddenly disappears after a little bump. I usually quickly lift and reapply the brakes to recover the regen whine
(I hate friction braking )

 

Reviving this thread as I've experienced this problem as well on my 2008 TCH. I'm wondering if the Prius brake problem is similar to what we're experiencing, and if Toyota will also have to widen THIS recall as well to include TCH's from past years. I disagree that braking is not affected. I definitely feel a surge and a loss of control. That perception needs to be corrected.

 

From the description I've heard from news reports apparently quoting Toyota, the problems sounds somewhat familiar, although to what extent, I'm not sure. When braking on poor road conditions when ABS detects a pending wheel lockup, the regen braking is released from the front wheels and the mechanical braking is applied to all 4 wheels. During the transition, there can be a short time where braking force is reduced as one system gives way to the other system. The fix apparently will be a software update to attempt to reduce this gap. If so, they will probably opt to reduce the amount of regen braking in favour of more mechanical braking.

It can be disconcerting when it happens. It feels like a forward acceleration, but it actually is a momentary decrease in deceleration. I've heard one story of a Prius shooting across an intersection, but from my experience the sensation is far worse than the reality of the situation. (Of course, any car with ABS can go shooting across an intersection if they were driving too fast for the road conditions). In any case, a "hard on the gas - hard on the brakes - no room for error" driver will probably find the problem much worse than others. I find tires make a big difference too. The problem rarely/never happens with my winter tires, but happened more noticeably with my summers, especially when they are cold.

 

Droid, thanks for the explanation. I would argue that a "momentary decrease in deceleration" is something that should be addressed. The goal should be a braking system which allows the driver to feel as if he is in control of his car throughout the braking process regardless of the road conditions. Apparently, Toyota just announced a recall of 270,000 Prius in the US and Japan to address this. If it's truly just a software fix, I'll be looking for a similar announcement for the entire range of hybrids.

 

I reported this some time back and it seemed like I was talking in giberish.. Now I see that there are others that experience the same thing!

https://www.greenhybrid.com/discuss/...braking-20162/

 

I haven't been the primary driver of our Prius but I have always viewed this transitional "lurch" as nothing more or less disturbing than the transition into ABS "mode" when that occurs. Once you understand the reasoning behind the causative factors you realize you have no cause to worry.

But I am given to understand the "lurch" in the 2010 is of a much more serious nature than in previous gens.

Actually even most Toyota/etc non-hybrid FWD and F/awd vehicles exhibit much the same "lurching" effect but for an entirely different reason. As you coastdown, throttle fully closed, below 10MPH you get a feeling as if being bumped lightly from behind. This effect is due to the transaxle upshifting in order to reduce the level of engine compression braking on the front wheels should the roadbed be somewhat slippery.

I took immediate notice of this when we first purchased our '01 F/awd RX300 but nowadays I have to initentionally focus on it in order to notice theeffect.