Felt the brake cut-out thing.....

ABS is only active on friction braking, not regenerative braking. You do need to push harder if you are not slowing.

 

That seems a reasonable explanation, but it also seems to describe a safety issue if the driver is not aware of the "transitional" nature of the ABS system. Methinks dealers should be telling new owners to be sure to slam on the brakes when driving on wet or icy pavement. Oh wait that isn't safe either.

I smell Toyota's next recall.

 

From the 07 Owner's Manual:

 

Yes those are normal instructions for ABS. I wonder if the 2010 manual mentions that one must push through the regen braking to get to the ABS?

 

I don't have a 2010 manual. Do you know someone who does? :madgrin:

 

One doesn't have to "push through regen braking" to get to ABS. One gets to ABS anytime the wheels slip while braking at speeds above six mph. In other words, if the wheels slip, regen stops automatically and you get ABS.

Tom

 

Thanks Tom. I would expect ABS to activate ANYTIME the wheels stop turning. If you are in regen braking and the wheels lock up, I expect it to activate friction braking and ABS, and THEN stop regen braking. Wheel lockup detection should function regardless of braking mode.

When it occurred, I knew the road was slippery and therefore was braking gently. I was very surprised to find the ABS did not engage when the wheels locked up. If this is by design, I'd call it a design flaw. One should not have to press harder to get ABS to activate. It should activate on wheel lockup, period. I love the car but I thought by 2009/2010, engineers had this stuff figured out.

 

My 2006 transitions very quickly from regen to ABS, without having to push harder. It's strictly a matter of wheel slip.

Perhaps the more aggressive traction control on the 2010 has raised the transition threshold?

Tom

 

Did you mean to say "less" aggressive? From my personal experience, the traction control is definitely less aggressive on the 2010. I've managed to spin the tires a few times on wet pavement.

 

The ABS does not operate effectively when [FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman]l [/FONT][/FONT][FONT=Arial,Arial][FONT=Arial,Arial]The limits of tire gripping performance have been exceeded. [/FONT][/FONT][FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman]l [/FONT][/FONT][FONT=Arial,Arial][FONT=Arial,Arial]The vehicle hydroplanes while driving at high speed on the wet or slick road. [/FONT][/FONT]
[FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman]n [/FONT][/FONT]Stopping distance when the ABS is operating on the wet or slick roads [FONT=Arial,Arial][FONT=Arial,Arial]The ABS is not designed to shorten the vehicle’s stopping distance. Always maintain a safe distance from the vehicle in front of you in the following situ-ations. [/FONT][/FONT][FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman]l [/FONT][/FONT][FONT=Arial,Arial][FONT=Arial,Arial]When driving on dirt, gravel or snow-covered roads [/FONT][/FONT][FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman]l [/FONT][/FONT][FONT=Arial,Arial][FONT=Arial,Arial]When driving with tire chains [/FONT][/FONT][FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman]l [/FONT][/FONT][FONT=Arial,Arial][FONT=Arial,Arial]When driving over bumps in the road [/FONT][/FONT][FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman]l [/FONT][/FONT][FONT=Arial,Arial][FONT=Arial,Arial]When driving over roads with potholes or roads with uneven pavement
[/FONT][/FONT]

 

In clarification, my earlier post was in reference to any braking--if you're not stopping quickly enough, push harder. I see a number of references here by posters referring to a sensation of wheel slippage under "gentle braking" and "regenerative braking". My point was only that braking is braking--apply more pressure if the job is not getting done, and don't release pressure if ABS engages. I did not mean to imply you have to push through a loss of braking sensation to get ABS braking. (I don't have any problems with braking on my Gen 3.)

 

I knew instinctively what to do to get the ABS to engage. I was just surprised to find that you can brake gently, lock up the wheels on ice, and have the ABS NOT engage. This is not the case on my Odyssey. If the wheels stop turning, ABS engages immediately. I could see someone reacting to wheel lockup on ice by letting off the brakes the way we did pre-ABS and getting into trouble.

 

My experience of the issue is a very very noticeable lurch forward. I thought at first that power was being applied, as I was breaking. I can reproduce the effect in the same spot in the road, every time. I've trained myself to slow down earlier, so that I can go over the spot without breaking, to avoid the effect. I think this should be fixed. It's not trivial IMO.

 

You have learned how the car reacts in that situation, and you have learned how to adjust your driving to avoid it. Maybe Toyota can fix it, maybe not. Maybe it is worse in the 2010, maybe not. If it is the same as in my 2007, I think it is no big deal. It is just a part of having a car with regenerative braking.

 

It's very marked at this specific location, and I wouldn't describe it as trivial or normal. The car lurches forward very strongly, resulting is a marked over correction and swerving to avoid a round-a-bout. I learned to avoid the spot, because I pass it every day and I know where it is. A car shouldn't behave this way. A new driver hitting this for the first time could lose control, especially in icy conditions. I notified Toyota, and I think they should go to the spot to see for themselves.

 

I upgraded from Gen II (2006) to Gen III and have the same daily commute. It is MOST ASSUREDLY more noticeable in the 2010. As I come to the turn to the parking lot at work, I am slowing. Just before the turn (about 3 feet) is a bumpy patch/small pothole that triggers this "feeling of acceleration" just as I am making the turn. Yes, I have learned to "slow to a crawl" before making this turn but it happens at unexpected times elsewhere. You just really have to experience it to understand it. It makes your heart skip a beat.

 

I called Toyota about this, and told them about a spot that reproduces the problem every time, but I've never heard back from them. They know about it, but they don't seem to care much.

 

Randall, would be interesting to see if you apply the Brakes harder if this same experience is able to be identified?

I think we need to do this so to provide Toyota with good things to track...

 

It was smoothed with asphalt so it will take a few months before it is rough again. I will find some railroad tracks to cross at different braking pressures. I think this "cut out" only occurs when light "regen" braking is in progress. Friction braking may or may not engage ABS on these "slight" bumps.

 

Not just one beat.

I'm new to Prius... and PriusChat. I sold my '02 VW GTI and upgraded to a '10V about three weeks ago. I've encountered this problem three times and it's scary. I live in in-town Atlanta, a city riddled with potholes and broken pavement. They cannot be avoided.

I've never experienced this sensation before while braking on dry pavement, not in any car I've owned or rented. I've rented a lot, a lot of GenIIs. This is not an ABS issue. An ABS + regen breaks? Maybe.

Toyota needs to figure this out before some gets hurt.