1. Attachments are working again! Check out this thread for more details and to report any other bugs.

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

    Joined:
    Jan 25, 2013
    149
    53
    0
    Vehicle:
    2008 Prius
    Model:
    N/A
    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

    Joined:
    May 11, 2005
    107,796
    48,995
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    no dash lights?
     
    #2 bisco, Mar 5, 2018
  3. PAUL SCHULTZ

    PAUL SCHULTZ Member

    Joined:
    Feb 5, 2018
    103
    66
    0
    Location:
    Michigan
    Vehicle:
    2008 Prius
    Model:
    Touring
    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
    valde3 likes this.
  4. SRQ

    SRQ Member

    Joined:
    Jan 25, 2013
    149
    53
    0
    Vehicle:
    2008 Prius
    Model:
    N/A
    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

    Joined:
    Aug 23, 2015
    1,014
    485
    0
    Location:
    Nh
    Vehicle:
    2017 Prius Prime
    Model:
    Plug-in Advanced
    An 08, definitly time for a brake fluid flush.
     
    #5 Lucifer, Mar 6, 2018
  6. Prius7Prime

    Prius7Prime Junior Member

    Joined:
    Dec 6, 2017
    58
    15
    0
    Location:
    Long Beach
    Vehicle:
    2012 Prius Alpha
    Model:
    Prime Advanced
    #6 Prius7Prime, Mar 6, 2018
  7. jerrymildred

    jerrymildred Senior Member

    Joined:
    Oct 28, 2016
    11,491
    14,100
    0
    Location:
    Tampa, FL
    Vehicle:
    2017 Prius
    Model:
    Two
    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
    Raytheeagle likes this.
(You must log in or sign up to post here.)