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Buzzing in my dashboard - defective relay?

Discussion in 'Gen 2 Prius Main Forum' started by RhythmDoctor, Jun 16, 2008.

  1. RhythmDoctor

    RhythmDoctor Member

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    I am getting a buzzing noise in the driver side of my dashboard every minute or two. It lasts about 2 seconds. It is very faint - passengers in the back seat cannot hear it, front passenger can barely hear it, but in the driver seat I am very aware of it, I have confirmed that it does not seem to occur in other Priuses. It sounds like there is an electromechanical relay that turns on (or off) every minute or so, and instead of clicking into place immediately, it balks. I thought it might be related to the thermostat, but it happens at all temperatures, even with the A/C turned off. I just noticed that it also happens after I turn the car off, and is very noticeable in my garage when I am outside the car (in other words, it may be happening inside the engine compartment.)

    Has anyone else here experienced this problem? If so, what was it, and how was it fixed? Or, can you suggest some reason why my Prius should do this while others do not?
     
    #1 RhythmDoctor, Jun 16, 2008
  2. qbee42

    qbee42 My other car is a boat

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    Sounds normal to me. The Prius uses an electrically driven pump to supply hydraulic pressure for the power brakes. The pump makes a buzzing or ratcheting sound on the driver's side down near the footwell under the dash. It operates every third time or so when you press the brake. It's easy to hear if you pay attention, and easy to miss if you have bad ears or loud music.

    There is a second pump that you hear right after power down. That one is the coolant transfer pump that stores hot engine coolant in a thermos bottle for the next power up cycle. It has more of a whirring sound.

    Tom
     
    #2 qbee42, Jun 16, 2008
  3. RhythmDoctor

    RhythmDoctor Member

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    Should this happen only while I am pressing the brake? Because it seems to happen anytime - including accelerating, gliding, and sitting still.
     
    #3 RhythmDoctor, Jun 16, 2008
  4. qbee42

    qbee42 My other car is a boat

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    If it is the brake actuator pump, it mostly runs when you press the brake. If the pressure bleeds down it can run on its own, but that doesn't happen very often. If you hear it running often and without the brake pedal, then you may have a pressure leak in your brake system. This happens sometimes. If you think that's the case, have the dealer look at it, as you don't want to take chances with your brakes.

    Tom
     
    #4 qbee42, Jun 16, 2008
  5. RhythmDoctor

    RhythmDoctor Member

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    Now that I've gotten the defective clock fixed (a different thread), I've gotten in the habit of looking at the clock and making a mental note of the time. The buzzing happens every 1-2 minutes all the time. So if there's a pressure leak in the brake system, it's a serious one.

    I've also started noting a rattle in the right side of the dashboard.

    My wife's brand new Prius does not have any of this behavior. Between the defective clock (which required an overnight stay at the dealer :mad: ), this buzzing noise, and the rattle in the dash, this is potentially the most defective car I've bought since my 1974 Ford Pinto. I'll be keeping the lemon law booklet nearby. :(
     
    #5 RhythmDoctor, Jun 16, 2008
  6. brad_rules_man

    brad_rules_man Hybrid electric revolutionizer

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    oh don't worry it's just bees buzzing in the dashboard. hehe just kidding. I hope that you get it fixed up and have no more problems! I get rattling in a few panels during the harsh cold of winter. I get the buzzing noise anytime there is brake activity, but not just during casual driving. That sounds a bit scary, and I wouldn't waste time dealing with that one.
     
    #6 brad_rules_man, Jun 17, 2008
  7. Bob64

    Bob64 Sapphire of the Blue Sky

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    Most likely the brake actuator pump. Try this. Start the car, shift into neutral with the parking brake on. Keep your foot OFF the brake. Do you still hear the sound every 2 minutes?
     
    #7 Bob64, Jun 17, 2008
  8. Grocked

    Grocked Green Patriot

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    Same noise in my 2008 Prius. I'm glad it appears normal...
     
    #8 Grocked, Jun 17, 2008
  9. RhythmDoctor

    RhythmDoctor Member

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    Thanks for the advice. I'm actually traveling in Iowa using a rental car (big-nice person SUV :eek:), so I won't be able to try this until Friday or Saturday.
     
    #9 RhythmDoctor, Jun 18, 2008
  10. RhythmDoctor

    RhythmDoctor Member

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    FYI, my wife's new Prius makes exactly the same noise, with about the same frequency. So I have concluded that this noise is not a defect. Thanks, everyone, for the suggestions. I'm glad the noise does not bother you as much as it does me. (Actually, now that I know it is not a defect, I am able to ignore it.)

    [​IMG]
     
    #10 RhythmDoctor, Jun 23, 2008
  11. Darthvisor

    Darthvisor New Member

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    I have a similar noise, it sounds almost like the CD is spinning up to play. happens every few minutes for only a few seconds. I can confirm its not the CD, just don't know what it is since I have had the car about a month and it just started making this noise a few days ago...
     
    #11 Darthvisor, Jul 15, 2008
  12. qbee42

    qbee42 My other car is a boat

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    Does the noise appear to originate around the CD player, or some other location?

    Tom
     
    #12 qbee42, Jul 15, 2008
  13. BooWilbury

    BooWilbury New Member

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    I have the same issue with my 2007 Prius; exactly as described. However, the 1-2 second buzz will happen every 20 seconds as I drive. Sometimes 15 seconds, sometimes 30, and rarely more than a minute. City or highway driving (braking or not, AC on/off etc). It will start buzzing from the time I unlock the door, and continue 3-4 times after the car is off.

    I have noticed it for the last few weeks; either because it has become louder, or more frequent. I'm fairly sure this wasn't the condition when I got it new, a year and a half ago.

    I took it in for service, and was told the noise was normal, the car checked out ok, and no repairs were needed. Still, I wonder....
     
    #13 BooWilbury, Aug 14, 2008
  14. GoodByeGas

    GoodByeGas Junior Member

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    Qbee42 post #2 described exact sound I get also. Its normal sound unfortunately. Took my 09 to the dealer service departmemt just to get that sound diagnosed. Tech and service writer said is brake hydraulic actuator. Totally normal. Get used to it or turn some music on. :)
     
    #14 GoodByeGas, Jul 18, 2018
  15. bisco

    bisco cookie crumbler

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    or fortunately, since it would be a few thousand dollar repair if it weren't normal.
     
    #15 bisco, Jul 19, 2018
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