Vehicle has inadequate brake pressure to remain in place upon startup after switching to drive/rever

Discussion in 'Gen 2 Prius Main Forum' started by SRQ, Mar 5, 2018.

  1. SRQ

    SRQ Member

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    My vehicle has started to roll despite me having my foot on the brake immediately after start; often times I'm ready to roll immediately after starting the vehicle and the brakes feel mushy until I pump them a few times. This runs the possibility of me rolling into another parked vehicle/obstacle or pulling out into a parking lot when I decide to to a start followed by an immediate shift to get started.

    The brakes work fine once the engine has been running. The vehicle has about 186k miles and I have not replaced the brake pads or had the brake fluid replaced or serviced in any way.

    I'm assuming that there's something going on with the pressure in the system; wanted to run this by you guys in case this leads to something serious or just needs a quick service.
     
    #1 SRQ, Mar 5, 2018
  2. bisco

    bisco cookie crumbler

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    no dash lights?
     
    #2 bisco, Mar 5, 2018
  3. PAUL SCHULTZ

    PAUL SCHULTZ Member

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    New vehicle to you? If not, then have you had issues with the brake actuator barking or buzzing? Any fluid leaks under the vehicle when parked? Could be a pressure leak due to an actuator failure. Could be a system leak due to old brake lines. Any evidence of fluid at brake cylinders (rear) or calipers (front)? Could simply be air in the lines and needs to be flushed/bled. Too many possibilities without further information. Like was asked.... any dash warning lights? any engine codes (assuming you have a code reader)?
     
    #3 PAUL SCHULTZ, Mar 5, 2018
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  4. SRQ

    SRQ Member

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    1. Not a new vehicle; bought it with 27k and now at 186k.

    2. What would the brake actuator barking/buzzing sound like (seems obvious but I haven't heard anything out of the ordinary)?

    3. I'll take a look for leaks.

    4. I'm thinking that it's simply air in the lines as well; the brake fluid reservoir has shown a slightly lower indication over time.

    5. No dash warning lights/codes.

    6. The issue is resolved after the engine runs for a few seconds, brake pressue comes back to normal and I don't have to worry about it rolling with mushy response from pumping the brakes.

    Thank you,
    -SRQ
     
    #4 SRQ, Mar 6, 2018
  5. Lucifer

    Lucifer Senior Member

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    An 08, definitly time for a brake fluid flush.
     
    #5 Lucifer, Mar 6, 2018
  6. Prius7Prime

    Prius7Prime Junior Member

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    #6 Prius7Prime, Mar 6, 2018
  7. jerrymildred

    jerrymildred Senior Member

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    That happened to me a couple years ago with my '05. Took it to the dealer thinking it was the accumulator. Turns out the 12V only had 8.5 volts. No codes. Everything else was fine. It was time for a new battery anyway, and that fixed it. If the accumulator doesn't have sufficient voltage, it takes extra time to build pressure.
     
    #7 jerrymildred, Mar 6, 2018
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