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2010 Prius making a buzzing sound when depressing brake pedal and sometimes even when you do not

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Ruben777, Aug 15, 2023.

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  1. Ruben777

    Ruben777 New Member

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    Hi I have a 2010 Prius with 76,000 miles.
    I was having an issue with a buzzing sound when you press the brake pedal, and sometimes when you do not press the brake and when you shut the car off., Then you would here a sort of hissing sound when you press the brakes

    No brake warnings lights ever came on the dash

    The dealer said it was the brake booster assembly was going bad.
    Then I took it to a repair shop and they said their scanning tool said the brake booster pump was bad.
    They replaced the brake booster pump

    After replacing it, its still making those same buzzing sounds, its just not as often as before.
    I called the repair shop that replaced that brake booster pump and told them it was still making that buzzing sound and they said the new part needs to adjust to the car it will evenutally stop after a few times turning on and off the car.

    Does this sound correct?
    Does it sound like the booster brake pump was going bad and needed replacing?


    thx

    Ruben
     
    #1 Ruben777, Aug 15, 2023
  2. ChapmanF

    ChapmanF Senior Member

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    In a Gen 3, there are both of these things under the hood:

    [​IMG]

    Either one can cause the symptoms you are describing. (Only the bottom one has the pump, but either one can be the reason the pump has to run).

    So if one of those units was replaced and the pump still has to run frequently, then either (1) the replacement unit is faulty, or (2) there's a problem in the other unit.

    The idea that the unit has to "adjust to the car" is pure woo.
     
    #2 ChapmanF, Aug 15, 2023
  3. Ruben777

    Ruben777 New Member

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    Thanks what was replaced was the brake booster pimp assembly.
    It does not run alot, it runs occasionally but not as often as before the brake booster pump was replaced.

    The Mechanic said when he put the scanner tool it showed as being bad so thats why it was replaced.

    If I hookup a friends scanning tool will it find if the brake booster pump assembly is bad too?

    thx

    Ruben
     
    #3 Ruben777, Aug 15, 2023
  4. bisco

    bisco cookie crumbler

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    itdepends on the scan tool. keep in mind, a brand new health brake booster makes a buzzing noise when you open the drivers door, and occasionally while driving. that's the pump pressurizing the system.
    on my 2012 with 86k, it buzzes 10-12 seconds upon opening the door first thing in the morning. this is much longer than when new, but still operating well.
     
    #4 bisco, Aug 15, 2023
  5. Ruben777

    Ruben777 New Member

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    Gm thanks , with the new brake booster pump assembly it does not buzz as frequently as before.
    With the new part It buzzes occasionally with the door open and occasionally when driving .

    Yesterday I noticed the brake fluid had spilled because he over filled the reservoir. He said he had to to get the scan tool to accept the new part so he had to over fill it. He also said he had to call the Dealer to match the new part with the car.


    The mechanic said he scanned and it showed the brake booster pump assembly as being bad. So that is why that part was replaced.

    He did not replace the other part, the brake booster pump assembly (accumulator).
    How would I know the the brake booster pump assembly (accumulator) is bad without a scan tool?

    I think I will have my friend scan it again to see if any codes show after two weeks, because the mechanic could of cleared the codes.
    I just want to be sure everything is ok.


    Any thoughts / recommendations?


    thx

    Ruben
     
    #5 Ruben777, Aug 16, 2023
  6. bisco

    bisco cookie crumbler

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    might be worth asking a dealer how much they want for a scan, aren't there any hybrid shoppes in LA?

    if you paid the dealer for the initial assessment, ask the for the codes
     
    #6 bisco, Aug 16, 2023
  7. ChapmanF

    ChapmanF Senior Member

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    It's a common misconception that the scanner tool can tell you what part is bad.

    The scanner tools can show you the diagnostic codes the car's computers have set. But the car's computers can only set codes that say what the car's computers saw. The computers don't have any way of knowing why they saw what they saw, so the codes aren't going to tell you that. They just can't. That's the part for the human to figure out.

    In the case of codes for the brake system, there are some codes that say "the fluid pressure couldn't be brought up to the right level" and some codes that say "power was sent to the pump for longer than should be necessary to bring the pressure up" and so on. Those are straight observations—the kind of things a computer in a car would be able to notice.

    As to why the pressure is dropping, why the pump has to run so long, or whatever, some human needs to figure that out. There are possible causes in both of those units, and the car's computer or a scan tool by itself can't do that diagnostic gumshoe work for you.

    Some mechanics will see that the description of a trouble code has the word pump in it, and then they'll say "the code said the pump was bad".

    Unfortunately, that's a case of really not paying enough attention to what the code in fact means.
     
    #7 ChapmanF, Aug 16, 2023
  8. Ruben777

    Ruben777 New Member

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    Thanks, I did not pay the dealer anything for the assessment.

    I will ask how much they want for a scan
    I will also ask my friend to rescan in two weeks see if any codes show up.


    Any other recommendations?

    thx

    Ruben
     
    #8 Ruben777, Aug 17, 2023
  9. TranquiloQuieto

    TranquiloQuieto New Member

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    Did you get that situation fixed ?
     
    #9 TranquiloQuieto, Aug 26, 2023
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