When I press the Power On button, I hear a slight grind

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by priusenvious1, Dec 26, 2012.

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  1. Paradox

    Paradox Prius Enthusiast / Moderator
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    Go try it without your foot on the brake. Of course, press the brake to start into ready but then remove it. Listen for the sound of what I am describing which happens right at exactly the same time your car made the noise at that point in the video. It would be too ironic IMO that it's not the part making the occasional noise that makes the same 'normal' noise at that same time each time during startup.

    And by flaps, I mean there are things in the vents which divert airflow to the floor, the windshield, the face vents, the recirc fresh air etc. I call those things flaps which do the diverting of air. you cannot see them since they are somewhere in the vents or behind the firewall etc but you can hear them.
     
    #61 Paradox, Dec 30, 2012
  2. bisco

    bisco cookie crumbler

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    it does sound like a vent door/flap. but do they move upon start up or only when you change with button?
     
    #62 bisco, Dec 30, 2012
  3. Paradox

    Paradox Prius Enthusiast / Moderator
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    Like I said, I just went out to test mine and mine did they adjusting sound even with everything hvac related upon startup. I was pretty sure it did it each time, which is what made me think yesterday or whenever it was i posted earlier in this thread I thought it may be a possibility.
     
    #63 Paradox, Dec 30, 2012
  4. Paradox

    Paradox Prius Enthusiast / Moderator
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    Ok, so I went out and tried this again.

    If you sit there continually starting into ready, shutdown, then restart it will not make the hvac vent re-positioning sound thing after the first start-up. But if you shut the car down, and press the lock button on the keyfob while sitting in the car after some time you'll hear the hvac vent re-positioning flap sound thing. Then restart and you'll hear it again at startup at the point in time I described. The car must close the vents so outside air cannot go in the car once it is shutdown and armed? I do not know, but at this point I'm leaning towards this being his problem and what I'd mention to the service tech in the service department. It's just too coincidental that the car does something 'normal' right at the same time the OPs sporadically makes a weird noise. Maybe a 'flap' is getting hung up or stuck on something?
     
    #64 Paradox, Dec 30, 2012
  5. bisco

    bisco cookie crumbler

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    i've noticed that sometimes mine are noisier than others. do not know if it's weather related or what.
     
    #65 bisco, Dec 30, 2012
  6. RRxing

    RRxing Senior Member

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    After revisiting the video, it sounds like the doors unlocking when the car is put in P, unless you changed that option. Then again, you said it's random. How many videos did you have to make before getting the one with the sound?

    I like puzzles. This one has got me. Let us know what you find out.
     
    #66 RRxing, Dec 30, 2012
  7. priusenvious1

    priusenvious1 Member

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    If that is the case, then great. But how would I know for sure? Any way to see/test them? Can I manually close flaps and then turn the car on? And why does it only happen when the car is cold?

    I already know that this will not reproduce the problem. The reason is because, I always just park the car for awhile and when I restart it even after an hour or two or more, it will not make the noise. The noise is most likely to happen after a longer time like overnight or parked out in cold weather for a long time. It usually doesn't happen after parked for a short time, or even at around 2 hours of parking. That being said, I'll try what you said anyway just in case.
     
    #67 priusenvious1, Dec 30, 2012
  8. priusenvious1

    priusenvious1 Member

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    OK, a new thing I noticed is that before you even start the car and you go near the car, the sound makes some noise. I found this out when I popped the hood after a cold night and I heard some sounds coming out for about 3-5 seconds. Now I've been waiting for that noise to stop before I start the car and so far no grinding noise has happened. I discovered this in the morning so we will see if it works out over the long term.
     
    #68 priusenvious1, Dec 31, 2012
  9. bisco

    bisco cookie crumbler

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    car makes lots of fun noises, no extra charge.:D

    are you sure you've owned this car for 2 months?:confused:
     
    #69 bisco, Dec 31, 2012
  10. priusenvious1

    priusenvious1 Member

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    OK so this kind of works. However, one time, it happened without even starting the car. The car was warm and I hit the brakes... After keeping my foot depressed on the brake, it happened again once. Weird one off...

    So whatever happens the first few seconds before the car starts up, also happens at other times too. Whatever that is, the combination of that plus holding my foot on the brake makes this sound.
     
    #70 priusenvious1, Jan 2, 2013
  11. bisco

    bisco cookie crumbler

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    i think the car is trying to tell you something. christine?o_O
     
    #71 bisco, Jan 2, 2013
  12. priusrat

    priusrat Junior Member

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    I just came across this thread. I can tell you that my 2010 Prius II with 52K on it makes the exact same sound intermittently at startup. (Thanks for the video.) I always have my foot on the brake when I start. The sound wasn't there when I first bought the car. Most of the time I don't have the car in P when I shut it off - dealer told me it was fine to shut it off in D.
     
    #72 priusrat, Jan 10, 2013
  13. priusbee

    priusbee Member

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    That noise is sounded like a vacuum pump that is not well lubricated.
    Is the fan power on or any accessories on? Turn off everything when you perform the power on.

    You need to locate that sound where it came from - that is the only hope you have to fix this issue.
     
    #73 priusbee, Jan 10, 2013
  14. priusenvious1

    priusenvious1 Member

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    The sound is clearly coming from the brakes in the front of the car. You can even feel it with your foot on the brake as the sound occurs.
     
    #74 priusenvious1, Jan 10, 2013
  15. priusbee

    priusbee Member

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    Here is a link about how brake booster work:
    HowStuffWorks "How Power Brakes Work"

    When you step on the brake, don't press it hard but just enough in order to activate the start button. See if that makes any different sound. Also, look at a leaking check valve in the vacuum booster.

    Since the car is new, talk to the dealer to see if they can replace the brake booster assembly under warranty due to this noise.
     
    #75 priusbee, Jan 11, 2013
  16. priusenvious1

    priusenvious1 Member

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    Yeah, when I start the car and only step on the brake for a very brief moment to do so, I can avoid the noise. But if I keep my foot on the brake for another second or two, it will happen. And it occasionally happens in times other than startup too.
     
    #76 priusenvious1, Jan 11, 2013
  17. priusbee

    priusbee Member

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    Get the dealer fix the problem. They can try to replace the Vacuum Booster or replace the check valve.
     
    #77 priusbee, Jan 11, 2013
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