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Brakes Stutter right before the car stops.

Discussion in 'Gen 2 Prius Main Forum' started by lowspeed, Mar 6, 2006.

  1. darelldd

    darelldd Prius is our Gas Guzzler

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    For me, I think this is it.

    There is a sensor that decides you're off the brake enough to engage creep. I think that creep is coming and going when you're right on the border with light brake pedal pressure. Just a guess, but it seems to work that way for me. I'll ask my tech when I next take it in.
     
  2. unruhly

    unruhly New Member

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    I'm gonna try a few stops in neutral on my way home.
    Although the creep power might add to the problem, I don't think it's causing it. It's a definate release of hydraulic pressure that you can hear as well as feel.
     
  3. paco-shalom

    paco-shalom Veteran Prius Owner

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    I'm having the same problem with my '05. It is especially noticeable when inching into a parking space (like in a garage). It is very difficult to do a slow, controlled motion for just a couple inches. As I let up on the brake, it goes from stopped to moving too fast with nothing in-between. This occurs in Reverse as well as Drive, as I try to back into parking spaces whenever it is safe to do so.
     
  4. lowspeed

    lowspeed Member

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    It seems like i'm feeling an hydraulic release as well. It's like it is releasing more then you actually want it to, so it actually causes me to press it a little firmer.

    So is it something i should definitly have the dealer check ?

    My only concern is that i think they are not that trained...
     
  5. Bob Allen

    Bob Allen Captainbaba

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    might be your spelling
     
  6. lowspeed

    lowspeed Member

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    Could be ... but that's not the point ... is it ?

    I fixed my first post ... thanks for the comment.
     
  7. Rancid13

    Rancid13 Cool Chick with a Black Prius

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  8. IMHYBRID

    IMHYBRID New Member

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    I have an 04 and a 06 and I had the 06 at the dealer for this noise and they found nothing. It is still not right and we are going to go back to the dealer. I agree something is different.
     
  9. V8Cobrakid

    V8Cobrakid Green Handyman

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    I think i am. I think we all have the same "problem".. the electric motor is used as 15% of your normal brakes. At 8mph, this can no longer happen, the electric motor has to start turning the other direction to start your so called "Idle"... so instead of getting 15% helping you slow down, it's now 295lb of touqe going with you... given it's not directly hooked up.. but to us drivers it feels like the brakes just let go.. in a sense.. around 8mph.

    it's perfectly normal. I learned that if you do a very very mild braking... 40mph to 0 in about 10 second (given this is how to get the best regenerative power out of the system).. you don't really feel that little "let go" as much... i used to just let off the brake at that time.. and let the car coast for a second.. or let up and slow the stopping pace.

    My previous example (brakes locking up at low speed during emergency stop) is because it doesn't anticipate that loss of braking power.
     
  10. V8Cobrakid

    V8Cobrakid Green Handyman

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    I also wanted to add real quick.. there is no real "Idle".. when you hit your brake, it's as if the car is in Neutral... ... i know i said the car does idle... but if you are at a light and you hold the gas and brake.. there is no pull at the wheels.. nothing.. because the PSD can spin freely and do it's thing on it's own...

    Ok.. it's normal.. it's rather hard to explain properly because it's completly different than a normal car in this low speed stopping... As for parking garages and such.. you will feel as if you hit the brakes because there is nothing really pushing the car foward... such as a Engine running at 900rpms constantly... that's power tied to the wheels that you get to brake against, causing a smooth braking sensation till you're stopped... because the car wants to keep moving.
     
  11. lowspeed

    lowspeed Member

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    Did you even bother to read what i wrote ?

    I said when the car comes to a stop. its already beyond the transition to mechanical breaking.
     
  12. Begreen

    Begreen Member

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    The behavior doesn't seem universal in the '06s. I have to do this type of braking frequently when getting on the ferry. Slow creep into position because I know the nose of the car is out there somewhere, but don't want to ding it on the car in front of me. So far I haven't felt it at all.
     
  13. Jaymanva

    Jaymanva New Member

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    The brake pressure is always regulated by the brake ecu unless the brake system is in a failsafe mode.

    My 2006 has been doing this about 50% of the time since day one.
    While slowing down to stop, if the brake pedal is released slightly in the 5> mph range the brakes go "er, er" and I can feel the brakes grab and release slightly.

    It sounds as if the brake pressure is realeased (by the brake accuator) just enough to allow the rotors to slip slightly and cause the pads to groan.

    I have not noticed this sensation in the 2004 or 2005 model. I think it may be due to a programing change in the brake computer software or a problem in the brake accuator??
     
  14. lowspeed

    lowspeed Member

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    I tried the suggestion on the other thread to go downhill and put on neutral ... Seems to work .... i did it a couple of time on a long stretch downhill

    This means that the brakes under normal condition don't get any real usage...


    Can others with the problem report back to see if this solved their problem ?


    Thanks !
     
  15. hobbit

    hobbit Senior Member

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    It's not a *problem*. It's a ... characteristic. You'll get
    used to it.
    .
    The profound increase in the number of Priii I've been seeing on
    the road coupled with the many "repeat questions" flying around
    here makes me think we've got a lot of relative '06 newbies. Time
    to start thinking about f2f gatherings again...
    .
    _H*
     
  16. lowspeed

    lowspeed Member

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    What are you talking about ? If the car stutters right before it stops on a mild stop it's not only annoying it IS a problem.

    Did you read the description of the problem ??

    GEEZ
     
  17. hobbit

    hobbit Senior Member

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  18. cwerdna

    cwerdna Senior Member

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    I posted about this exact behavior at http://priuschat.com/index.php?showtopic=1...92&#entry199492. I'm still unsure if it's normal. I'm past 2K miles on my 06 Prius and it's also intermittent when coming to a stop below 10 mph (more like below 5 mph).

    I'm still unsure if it's normal, normal only for 06s [due to some changes, possibly firmware) or a defect.

    I test drove an 04 Prius back in 03 and I didn't notice this then, but that was more only experience driving a Prius prior to owning one. I'm going to try coming to a stop in neutral and B later tonight.
     
  19. Ken Cooper

    Ken Cooper New Member

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    On my two year old '04 I've always assumed that this little null is the transition between regenerative braking and mechanical braking.

    Never thought it was serious enough to mention when the car was at Toyota being serviced.
     
  20. ceric

    ceric New Member

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    I move my Prius into a very narrow 1-car garage very slowly (5-inch each side), and put it to stop with 5 inch front and rear. My '05 Prius stops smoothly. Never experience such problem people talk about here. Please get your Prius checked and demand Toyota to fix it.