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Prius makes "toot" sound upon cold startup

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Patrick Wong, Jun 15, 2009.

  1. Patrick Wong

    Patrick Wong DIY Enthusiast

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    My 2004 has 80K miles and we again are visiting the Tucson, AZ area.

    As you know, it is necessary to depress the brake pedal when starting the car. Yesterday I noticed that I hear a "toot" sound, almost like "breaking wind", when I depress the brake pedal before the car has started. If I pump the pedal it will toot twice, then stop. Once the car has started then no unusual noises occur. The braking system works fine, no warning lights.

    After driving the car for a while, turning it off, then restarting it, I do not hear the noise.

    I assume that the sound is coming from the brake pressure accumulator pump (definitely not from me.) If anyone has also noticed this or can offer another hypothesis about the source of the sound please reply.
     
    #1 Patrick Wong, Jun 15, 2009
  2. efusco

    efusco Moderator Emeritus
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    I'd ask Patrick Wong he's our Prius exper....oh, wait...hmmmm...

    You don't think it's a friction rub of some sort Patrick? Could there be a little air in the brake line/accumulator?
     
    #2 efusco, Jun 15, 2009
  3. qbee42

    qbee42 My other car is a boat

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    I got that sound from my 2006, but only when I was traveling out west last fall. I assumed it had something to do with the higher elevation and temperature variations. Mine sounded like the brake accumulator or master cylinder. I had the dealer check it when I got back, but by then it was quiet.

    Tom
     
    #3 qbee42, Jun 15, 2009
  4. F8L

    F8L Protecting Habitat & AG Lands

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    I think you need to stay out of Arizona! It's placed a hex upon your car Patrick. :)
     
    #4 F8L, Jun 15, 2009
  5. Mpress

    Mpress Junior Member

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    Is it supposed to be silent when you press the brake on startup? My 2007 makes a whirring noise when I step on the brake to start it.
     
    #5 Mpress, Jun 15, 2009
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Actually we are very close to buying a home here, so the Prius will have to get used to this area whether it likes it or not... :rolleyes:

    The whirring noise is normal and comes from the brake pressure accumulator pump. You can make the noise appear on demand by repeatedly depressing the brake pedal when the car is READY.
     
    #6 Patrick Wong, Jun 15, 2009
  7. jayman

    jayman Senior Member

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    Boost pump? Accumulator? I know an FJ owner (The FJ also has electric assist brakes) and he happened to notice that noise when starting up in his garage, hitting the brakes, and backing out

    It was LOUD as he could hear it over the motor

    Dealer changed the entire brake boost/cylinder assembly under warranty. Apparently it was some sort of defect, hasn't made the noise since
     
    #7 jayman, Jun 15, 2009
  8. kevinwhite

    kevinwhite Active Member

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    Isn't this the brake actuator noise that's been refered to many times? If so it is harmless.

    http://priuschat.com/forums/toyota-.../29211-tsb-br001-07-brake-actuator-noise.html

    kevin
     
    #8 kevinwhite, Jun 15, 2009
    1 person likes this.
  9. jdenenberg

    jdenenberg EE Professor

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    Harmless perhaps, but irritating as it gets worse and happens whenever the brake pedal is pushed. My 2004's "Toot" was eliminated (air bubbles removed) by bleeding the right front brake (at the dealer as a specialized computer interface is required).

    JeffD
     
    #9 jdenenberg, Jun 15, 2009
  10. JayGoldstein

    JayGoldstein Member

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    That's what was making the noise in my car. The actuator was replaced just before the 3 yr./60,000 km warranty was to expire. Start ups now are nice and quiet.
     
    #10 JayGoldstein, Jun 15, 2009
  11. efusco

    efusco Moderator Emeritus
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    Did your wife have a goofy grin on her face when this happened?
     
    #11 efusco, Jun 15, 2009
  12. galaxee

    galaxee mostly benevolent

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    that's the tsb issue. others have called it "barking" or "honking" or whatever. we had it, that's why DH replaced the actuator.
     
    #12 galaxee, Jun 15, 2009
  13. Chuck41

    Chuck41 New Member

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    Patrick

    I have had this toot the last few days when I startup and yes I ask my wife if it was her. My wife always says its not me even if it is.

    I shut off my baby when I got home and then started it up but it did not occur again.

    I have had my baby for 1 year now and this is the first time (the last few days) I have heard this toot.

    I was doing a search for this noise when I found this thread.

    Chuck
     
    #13 Chuck41, Jun 15, 2009
  14. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Thanks for the responses and the reference to TSB BR001-07! The noise has not reappeared over the past few days. Good to know that I can ignore the noise if/when it returns.
     
    #14 Patrick Wong, Jun 18, 2009
  15. howardbc

    howardbc Member

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    I have a 2008 and I've noticed recently that my car makes an infrequent, random sound like a very low horn toot when I first start it up and it is still in Park. I have around 11k miles on it. I will mention the sound to the dealer when I take it in for its next standard service appointment. I'll ask about the actuator. I do not have an after-market alarm system and I don't think the sound is actually the horn. It's more like a low squeak - not constant - just occasional. It goes away when I put the car in Reverse and then Drive.
     
    #15 howardbc, Sep 17, 2009
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