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Replaced 12v, constantly beeping and no power brakes

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Knoglet, Jun 14, 2020.

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  1. Knoglet

    Knoglet New Member

    Joined:
    Jun 14, 2020
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    Location:
    Fayetteville, AR
    Vehicle:
    2005 Prius
    Model:
    LE
    So I'm not really a Prius guy, my family just bought this car so we can all use it to commute because we have a bunch of gas guzzlers. Anyway, it's not in the best shape.

    When I first got the car I did some general maintenance, oil, air filters, all that. It also kept saying something about parking on a flat surface, I found out that is usually the fault of the 12v battery.

    So I went ahead and bought a new 12v battery and put it in myself. I didn't do anything so the Prius could keep it's memory because I really didn't mind, I kinda wanted it to reset anyways.

    I changed the battery and upon starting it back up, as soon as I press the brake pedal it began to beep, constantly, just bee- etc. And the brake pedal was extremely hard to push and was very sensitive. AndIAnd thelthe BRAKE light is on, the VSC is on, and the ABS is on, I've looked and looked for answers on this and I've found similar problems but never this exact one.

    Does anyone have any suggestions?
     
    #1 Knoglet, Jun 14, 2020
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,797
    48,996
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    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    sounds likea bad break actuator
     
    #2 bisco, Jun 14, 2020
    edthefox5 likes this.
  3. TMR-JWAP

    TMR-JWAP Senior Member

    Joined:
    Aug 12, 2016
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    Location:
    Columbia, SC
    Vehicle:
    2007 Prius
    Model:
    Touring
    There's a black box just to the left of the 12v battery. It's part of the brake system. (the brake control power supply assembly, Toyo #89680-33010). This box is normally unplugged and removed to allow better access to the 12v battery. Any chance you forgot to connect it back up, or the connectors got knocked loose, broke a wire?

    When you first start the car, do you hear any loud humming noise? That's typically the brake actuator pump running to pressurize the system. If there's no noise, something not letting the pump run. Whether that's pump motor failure, bcpsa, relay failure, or what, will need some troubleshooting.
     
    #3 TMR-JWAP, Jun 14, 2020
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