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High pitched whine when braking

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by Snowball, Jan 8, 2014.

  1. Snowball

    Snowball Junior Member

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    I've noticed more and more that when I am braking that I heard a high pitched whining noise. Sort of this ultrasonic type sound. It will only go away if I depress the brake pedal very firmly after being completely stopped. However every so often the firm press will not stop the noise. I hear it more in the evening on the way home than in the morning to work, though I may not be paying attention as much in the A.M. due to morning brain fog.

    Does this happen to anyone else? I don't hear it any other time. I'm worried something is wrong with my inverter.

    Thanks.
     
    #1 Snowball, Jan 8, 2014
  2. bisco

    bisco cookie crumbler

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    you're regenerating electricity man!(y) theya ll whine to some extent. when you press hard, you're engaging the friction brakes, don't do it!:p
     
    #2 bisco, Jan 8, 2014
  3. Snowball

    Snowball Junior Member

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    Ok. I only press hard once I'm completely stopped to get the whining to stop. Because it's still whining when I'm completely stopped! I don't think I'm still generating electricity when I'm not even moving.
     
    #3 Snowball, Jan 8, 2014
  4. bisco

    bisco cookie crumbler

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    ah, sorry, misunderstood. it's making the whining noise while your stopped?
     
    #4 bisco, Jan 8, 2014
  5. Snowball

    Snowball Junior Member

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    Yes, the sound starts when I press the brake to slow, and it continues to whine after I have already stopped. While I am stopped, I have the brake held in a static position to keep the car from rolling. From that pedal position, I have to press even further (mash the brake pedal down) to make the sound stop.
     
    #5 Snowball, Jan 9, 2014
  6. Mr Gee

    Mr Gee Member

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    In the first couple of weeks of ownership, we kept looking out for the ambulance that never showed
     
    #6 Mr Gee, Jan 9, 2014
  7. bisco

    bisco cookie crumbler

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    since mr gee has confirmed your experience in his c, it sounds like it might be normal. but i have never heard it in my 3 pri or 2 hycams.
     
    #7 bisco, Jan 9, 2014
  8. Mo G

    Mo G Member

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    Mine does it too. I think its the regen brake initiating. That's all. I think it's a normal part of the way the prius c brakes work. First it initiates the regen brake before the friction brake. That makes sense to me. Because I don't think the car can differentiate and apply only the friction brake while the vehicle is stopped. Someone correct me if I am wrong.
     
    #8 Mo G, Jan 13, 2014
  9. bisco

    bisco cookie crumbler

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    re gen is only active down to 6 mph, then it's pure fiction.
     
    #9 bisco, Jan 13, 2014
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