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hum coming from rear while car is off

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Papito23, Jan 14, 2016.

  1. Papito23

    Papito23 Junior Member

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    Walked into my garage where my 2011 Prius (have owned for 11 months, now at ~78K miles) had been sitting for about 4-5 hours after being used for a 4 mile trip. I heard a quite battery hum from the rear for about 1-2 minutes. I've heard this before... (it is not unlike the hum you hear in the front when opening the driver's door after the car has been sitting a bit.... and I've noticed that the duration of this front hum seems to be correlated with the time since last drive?).

    No clue what is was... Ideas? Thanks.
     
    #1 Papito23, Jan 14, 2016
  2. bisco

    bisco cookie crumbler

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    just an evap emissions test, nothing to see here, move along. kinda freaks you out the first time though, don't it?:p
     
    #2 bisco, Jan 14, 2016
  3. Montgomery

    Montgomery Senior Member

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    Its the little things like this that consistently tell me that Toyota really spends a lot of time on research and development regarding the Prius Hybrid. Ok, so Hyandai and Chrysler are moving in. Hope they pay as much attention to the details!!
     
    #3 Montgomery, Jan 16, 2016
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Soon after we got the car I had it jacked up and was taking a look at the underside, hours after driving. The strange noises started up while I was under there, and freaked me RIGHT out, lol.
     
    #4 Mendel Leisk, Jan 16, 2016
  5. Papito23

    Papito23 Junior Member

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    Weird... ok, thanks guys!
     
    #5 Papito23, Jan 18, 2016
    Xterra72 likes this.
  6. David Beale

    David Beale Senior Member

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    The sound you hear when you open the drivers door is the brake system accumulator pump building up pressure getting ready for you to drive.
    The sound you heard after a number of hours (it's in the owners manual) is, as posted above, the system testing for leaks in the evap. system.
    There are many -other- sounds the Prius makes as well. They are listed in the owners manual. Oh, and they are all "normal". ;)
     
    #6 David Beale, Jan 20, 2016
  7. Montgomery

    Montgomery Senior Member

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    The computer for this car is constantly checking the status of the vehicle. So, as an example, if you drive across the desert for 2 hours and stop at a hotel for awhile, the car will continue to monitor itself as it "cools down". Everything that was "on" during the 2 hour trip gets checked by the computer, like the AC pump, evap system, etc. You really did purchase a very complex vehicle. One that is ahead of the game, in my humble opinion.
     
    #7 Montgomery, Jan 20, 2016
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