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Normal noise from brake master cylinder/ABS unit?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by phobix, Apr 19, 2014.

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  1. phobix

    phobix Junior Member

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    Hello Everyone,

    I have leased my 2012 prius since April 2012 and about a year ago I began to notice the following noise originating from the master cylinder/ABS unit. The noise happens if I push the pedal firmly to the floor and occasionally during regular braking. The braking system seems to be working fine and regen braking is functional. I am wondering if this noise is a sign of an imminent failure. The reason I am asking is because I just decided to buy back the prius off lease and I still have factory bumper to bumper warranty available and have heard horror stories concerning the cost of a replacement ABS unit on the Gen III Prius.

    Listen to audio recording

    Video version here:
    WeVideo

    Thanks in advance
     
    #1 phobix, Apr 19, 2014
  2. edthefox5

    edthefox5 Senior Member

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    I believe there is a TSB for that. Someone will come along shortly and point it to you. Or search.
     
    #2 edthefox5, Apr 19, 2014
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  3. JC91006

    JC91006 Senior Member

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    This sound you are describing is brake actuator noise, all prius cars make this sound. If there is a problem, you would have a dtc or dash light to warn you the system has a fault.

    The was a recall on early 2010 models to replace the brake booster, but no recall on 2012 models

    SM-N900P ?
     
    #3 JC91006, Apr 19, 2014
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  4. phobix

    phobix Junior Member

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    This is certainly reassuring to hear that this is a normal noise. Did you actually listen to the recording? I used my iphone and had it placed adjacent to the ABS unit while my wife was pushing on the brake pedal.
     
    #4 phobix, Apr 19, 2014
  5. JC91006

    JC91006 Senior Member

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    I was going by your description only, I need a computer to hear the sound.

    SM-N900P ?
     
    #5 JC91006, Apr 19, 2014
  6. edthefox5

    edthefox5 Senior Member

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    Went to listen to it but requires a download. No thanks.
     
    #6 edthefox5, Apr 19, 2014
  7. phobix

    phobix Junior Member

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    As an IT professional I should know better, I completely understand your concern. I will embed a YouTube version of the audio clip a little later this evening. Thanks for your input
     
    #7 phobix, Apr 19, 2014
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  8. PriusInParadise

    PriusInParadise Member

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    It is the normal sound of the brake hydraulic pump. The pump runs as needed to maintain hydraulic pressure in the brake accumulator. Depressing and releasing the brake pedal will make the pump run, as will normal braking. It will not do it on every application, but only when needed to maintain pressure.

    The hydraulic pump will also run when first opening the driver's door after being parked for several hours.

    If you hear this repeatedly while in Ready mode, without depressing the brake pedal, there may be a problem.
    Some Gen II's and Camry Hybrids are experiencing internal pressure bleed-down in the brake accumulator that causes the pump to run every 20 seconds or so.
     
    #8 PriusInParadise, Apr 19, 2014
  9. phobix

    phobix Junior Member

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    Hopefully this is acceptable for those of you with reservations on downloading, I am struggling at the moment in trying to edit a video using chromebook.
     
    #9 phobix, Apr 19, 2014
  10. edthefox5

    edthefox5 Senior Member

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    He's not referring to the rattle snake sound of the brake vacuum pump is he? Never listened to his sound post.
    The car always made that sound.
     
    #10 edthefox5, Apr 19, 2014
  11. JC91006

    JC91006 Senior Member

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    Would this pose a possible safety risk? Another recall coming?


    SM-N900P ?
     
    #11 JC91006, Apr 19, 2014
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  12. phobix

    phobix Junior Member

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    Thank you for the clear explanation, makes absolute sense. Fortunately, I am not hearing this sound repeatedly.
     
    #12 phobix, Apr 19, 2014
  13. phobix

    phobix Junior Member

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    For those of you who do not want to download the file I have posted a video here:

    WeVideo
     
    #13 phobix, Apr 19, 2014
  14. JC91006

    JC91006 Senior Member

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    That sound is not normal, I would have it addressed under warranty before it runs out

    SM-N900P ?
     
    #14 JC91006, Apr 19, 2014
  15. phobix

    phobix Junior Member

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    It didn't sound right to me either. Presumably you have never heard this sound from your own Gen III prius?
     
    #15 phobix, Apr 19, 2014
  16. JC91006

    JC91006 Senior Member

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    Never heard that sound, sounds alarming

    SM-N900P ?
     
    #16 JC91006, Apr 19, 2014
  17. edthefox5

    edthefox5 Senior Member

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    That may be the pump normal sound just recorded in a weird angle. Where is the mic being placed to record that?
     
    #17 edthefox5, Apr 19, 2014
  18. edthefox5

    edthefox5 Senior Member

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    And why is there an abs pump on the ground there lol. Did you find someone with that weird sound too?
     
    #18 edthefox5, Apr 19, 2014
  19. edthefox5

    edthefox5 Senior Member

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    Whatever it is should be covered under 3/36 though. Hopefully you have less than 36,000 miles :eek:
    Take it in asap so it doesn't leave you on the side of the road.
     
    #19 edthefox5, Apr 19, 2014
  20. phobix

    phobix Junior Member

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    The mic was roughly roughly 3 inches away from the ABS unit. I had my wife depress the brake pedal to reproduce the problem while I had the hood open. This same sound is audible from the cabin albeit a little less pronounced.
     
    #20 phobix, Apr 19, 2014
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