2005 Prius 142k whining/humming noise...

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by dpeverhart, Jan 17, 2015.

  1. dpeverhart

    dpeverhart Member

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    The noise is only noticeable at speeds over 45 mph. The sound increases in volume when you let off the gas. It sounds like a whining or humming noise. There are no codes. I even hooked up Toyota Techstream and it shows no issues. It drives normal, no problems.

    I thought it was either the inverter or the transmission. The first thing I tried when drain and fill the transmission fluid. The fluid coming out looked and smelled normal so I refilled with Toyota WS and drove with no difference in the noise or performance. The next thing I tried was replacing the inverter. After replacement the noise is still the same. The inverter is from a 2006 Prius with 104k.

    One other thing I would add is that when I put the car in neutral while it's whining at speeds over 45-50 mph, the noise goes away.

    I'm out of ideas and wanted to see if anyone has any suggestions. I suppose it could be the transmission but it works as it should.

    Thanks
     
    #1 dpeverhart, Jan 17, 2015
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  2. JC91006

    JC91006 Senior Member

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    tire sound?
     
    #2 JC91006, Jan 17, 2015
  3. dpeverhart

    dpeverhart Member

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    I don't think so because it goes away when in neutral.
     
    #3 dpeverhart, Jan 18, 2015
  4. JC91006

    JC91006 Senior Member

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    No sound coming to a stop?
     
    #4 JC91006, Jan 18, 2015
  5. dpeverhart

    dpeverhart Member

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    No, it's only at speeds above 45-50 mph and gets louder when I let off the gas.
     
    #5 dpeverhart, Jan 18, 2015
  6. jdenenberg

    jdenenberg EE Professor

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    You are hearing the inverter switching rate. It could be coming from one of the MGs or from the inverter itself (most of them do sing when sourcing/sinking battery current) and putting the system in neutral idles the HV battery.

    JeffD
     
    #6 jdenenberg, Jan 18, 2015
  7. dpeverhart

    dpeverhart Member

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    Since I changed the inverter and it still makes the same noise does mean it's coming from one of the MGs?
     
    #7 dpeverhart, Jan 18, 2015
  8. jdenenberg

    jdenenberg EE Professor

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    It is normal to hear a "whine" whenever the battery current increases to significant levels (both when accelerating or significant regenerative braking). You will also hear this on your AM radio, especially when tuned to a weak station.

    JeffD
     
    #8 jdenenberg, Jan 18, 2015
  9. dpeverhart

    dpeverhart Member

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    Yes, and I hear it from our other Prius but the noise is insignificant. On this 05 Prius it is very loud
     
    #9 dpeverhart, Jan 18, 2015
  10. SugarPine

    SugarPine Junior Member

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    Did you ever find a solution to the noises? My 2004 is doing the same thing especially at 47 mph. Very strange humming or whining. Gets louder when I let off the gas.
     
    #10 SugarPine, Dec 26, 2023
  11. bisco

    bisco cookie crumbler

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    tires? wheel bearing?
     
    #11 bisco, Dec 26, 2023
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