How many times is Brake booster accumulator supposed to cycle in a minute?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by weapon, Aug 22, 2026 at 9:09 PM.

  1. weapon

    weapon Junior Member

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    I parked my 2010 prius today and noticed the Brake booster accumulator cycling while I sat in silence. How many times is the Brake booster accumulator supposed to cycle in a minute? Will bleeding the brakes solve this as I just change brakes/rotors and fluid a month ago or so. Is this the sign of it needing to be replaced? I am having no braking issues and no dash warnings.


     
    #1 weapon, Aug 22, 2026 at 9:09 PM
  2. rjparker

    rjparker Tu Humilde Sirviente

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    A good brake actuator will not cycle in a minute while you sit in silence. A weak brake actuator may cycle every 10 seconds.

    The brake actuators do go bad but Toyota does not consider them bad until they code. The real problem is when it takes too long to build pressure.

    A complete Techstream driven bleed may resolve it for one or two days.
     
    #2 rjparker, Aug 22, 2026 at 9:29 PM
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  3. weapon

    weapon Junior Member

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    It cycled 3 times in that video alone. That was after a long drive and then parked. But no codes or other issues so far. I will try to bleed the brakes again.
     
    #3 weapon, Aug 22, 2026 at 9:31 PM
  4. rjparker

    rjparker Tu Humilde Sirviente

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    My point was a bleed will not fix it longer than one or two days. Been there done that. Gen2 and gen3 Prius wear out brake actuators.

    Basically your video indicates its getting old. The brake booster pump is likely fine but the master cylinder/abs/skid ecu assembly is leaking internally.

    A complete failure can suddenly cause significantly harder braking and much longer stopping distances, sometimes causing collisions.
     
    #4 rjparker, Aug 22, 2026 at 10:20 PM
    Last edited: Aug 22, 2026 at 10:28 PM
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