Noise coming from the back seat speaker

Discussion in 'Gen 4 Prius Technical Discussion' started by nahh, Jun 23, 2018.

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  1. nahh

    nahh Junior Member

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    Hi. Does anyone encountered a noise that is coming from the passenger backseat speaker? When the car isn't moving the noise can be heard mostly for passengers in the back, but once you start driving at ~100km/h you can feel like you're outside in the drivers seat.

    It happens every once in a while (twice a month~) and goes completely away after you turn off the vehicle and turn it back. Also a very strange thing is that once you open & close passenger doors it goes away for a few seconds and then comes back.

    I have some videos if anyone is interested :)
    1) Dropbox - IMG_7105.MOV
    00:00 - 00:30 - the car is not moving, but the noise is audible
    00:30 - car is moving and the noise increases with the speed

    2) Dropbox - IMG_7344.mov
    00:00 - 00:30 the car is standing still, noise is audibble
    00:30 doors are opened & closed. noise goes away
    00:43 noise comes back

    The dealership says this is normal because the battery fan sometimes turns on and is related with hybrids. I find it hard to believe because once the noise was audible even though it was not so hot outside (20C or something) and the car was left in the underground parking. Does anyone else have this problem? Any thoughts on this?
     
  2. alanclarkeau

    alanclarkeau Senior Member

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    Where was your microphone for the recording? I couldn't really work out which noise you were referring to.

    The hybrid battery fan runs no matter what the temperature - my hearing isn't great, and I can only hear it if I try hard. I'm not certain, but I think the battery fan varies according to the hybrid battery temperature - not the ambient. The battery temperature will go up and down by being charged/discharged.
     
  3. nahh

    nahh Junior Member

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    The phone was near this speaker Dropbox - f.jpg
     
    #3 nahh, Jun 23, 2018
    Last edited: Jun 23, 2018
  4. alanclarkeau

    alanclarkeau Senior Member

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    How close to the speaker is the microphone?

    The hybrid fan is right next to that, on the corner below the seat itself - the LH arrow points to the main vent where the fan and filter are, the RH arrow - nobody really knows what it's there for
    upload_2018-6-23_19-55-41.png
    upload_2018-6-23_19-57-52.png
     
  5. dubit

    dubit Senior Member

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    All I hear is what sounds like a fan running - which is normal.

    Could it be the screen on that fan is getting caked up causing that fan to run faster than what your used to? I just cleaned mine and it was pretty dirty.
     
  6. nahh

    nahh Junior Member

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    It could be that it's coming from the vents and not the speaker. But is it normal that the noise increases as your speed increases? Opening the door and closing it makes the noise go away for 10seconds and once you restart the car it goes away completely?
     
  7. alanclarkeau

    alanclarkeau Senior Member

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    Try putting your microphone next to the grille and move it back to the speaker and back again - listening to the resulting recording might give you an idea of where it's coming from. Or use a makeshift stethoscope to listen.

    I'm probably not a good candidate, suffering from Tinnitus, I don't tend to hear those sorts of sounds unless I strain to hear. Hopefully someone else will chime in with an answer.

    But that's odd that it goes away when you open or close a door - again, hopefully someone else has an idea.
     
  8. RCO

    RCO Senior Member

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    Hmm. There's a post almost deaf as me! :whistle:
     
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  9. dubit

    dubit Senior Member

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    One sure way to confirm the source would be to remove the door panel. It's not very hard to do on most vehicles, doubt it'd be any different on a Prius.
     
  10. sam spade 2

    sam spade 2 Senior Member

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    I don't think that detracts from the fan theory at all.
    With the cabin completely closed, there should be slightly more "drag" on the fan.
    The same thing might happen if a window is just cracked open a bit.
    And air pressure differences might explain the sound difference when going down the road too.
     
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  11. nahh

    nahh Junior Member

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    It's coming from the battery vents. Is it normal that with speed increase the fan noise increases? Is very noticeable even for the driver, not only for the passenger.
     
  12. sam spade 2

    sam spade 2 Senior Member

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    I thought that had been covered already.
    YES when any fan runs faster it makes more noise.
    But most owners here report that their fan noise is barely audible, no matter how fast it runs.

    So.....you need to check yours out and at a minimum clean the screen and fan blades and check for obstructions.
    It is also possible that the fan motor is going bad.
     
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  13. alanclarkeau

    alanclarkeau Senior Member

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    Mine is silent - but my 65 year old ears aren't perfect, particularly at higher frequencies. I can hear it if I put my ear to the grille after a long drive and leave the car "ON", but can't hear it from the driver's seat.

    Yes, it will vary in speed - but technically it should be in relation to temperature of battery (which can vary considerably from ambient temperature), rather than speed. It could be worth asking your dealer again.
     
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  14. Starship16

    Starship16 Senior Member

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    I've never heard that fan come on. But maybe it's because of all the other cabin noise. And I've never heard it when the car is stopped.

    How do we clean the screen? I just use a powerful vacuum and place the suction over the vents back there. Do we have to remove the seat?

    This picture is from another forum. Where is the fan and screen that needs to be cleaned?

    IMG_0790.jpg
     
  15. dubit

    dubit Senior Member

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    deleted - mistakenly thought this was in the Prius C forum
     
    #15 dubit, Jul 1, 2018
    Last edited: Jul 1, 2018
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  16. alanclarkeau

    alanclarkeau Senior Member

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    That's not a Gen 4 - the vent isn't there on Gen 4 - it's more here:
    upload_2018-7-1_23-12-28.png
     
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  17. alanclarkeau

    alanclarkeau Senior Member

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    That doesn't look like a Gen 4 either? The vent is on the wrong side.
     
  18. sam spade 2

    sam spade 2 Senior Member

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    Maybe I should have said intake rather than screen.
    You have a 2 year old car. Unless it is WAY dirtier inside than normal......like from shedding pets......that should be fine for years to come.
    Do try not to be paranoid. ;)
     
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  19. dubit

    dubit Senior Member

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    my apologies - for some reason I thought "Prius C".
     
  20. Starship16

    Starship16 Senior Member

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    Thanks Sam. It's very clean, thankfully. I pick up the pizza crust. :LOL: And I also meant to say "intake." I got 2 off them on each corner of the lower seat.

    I has to edit this. I could have swore my car also had that long skinny vent as shown in the photo. It does not.
     
    #20 Starship16, Jul 1, 2018
    Last edited: Jul 1, 2018
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