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

Brake fluid change at two year service?

Discussion in 'Prime Technical Discussion' started by GT4Prius, Apr 24, 2019.

  1. ZipZap

    ZipZap New Member

    Joined:
    Jan 7, 2024
    7
    2
    0
    Location:
    Oregon
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    I tried the invalid mode procedure on my 2017 Prius Prime, but it does not appear to work. Any suggestions?
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,604
    38,179
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Did you have parking brake set? It has to be, not sure why, but if it isn’t car won’t go into invalid mode.
     
  3. ZipZap

    ZipZap New Member

    Joined:
    Jan 7, 2024
    7
    2
    0
    Location:
    Oregon
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    Yes. Thanks for your help.
     
  4. ZipZap

    ZipZap New Member

    Joined:
    Jan 7, 2024
    7
    2
    0
    Location:
    Oregon
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    Actually, now I think I have bigger problems. Yesterday, after trying unsuccessfully to achieve invalid mode, I heard somewhere that invalid mode was only needed for the rear brakes. So I decided to replace the brake fluid in the reservoir by applying suction to the nipple on the right front wheel. I was able (with great difficulty) to lower the fluid level in the master cylinder below the lower limit mark. At that point I gave up for the day. This morning I tried the invalid mode procedure again, but noticed the brake pedal does not feel normal and I hear a clunk from the master cylinder every time I press the pedal. If that wasn't enough, now when I open the driver's side door, I do not hear the electric pump turn on. Have I really messed things up?

    Thanks.
     
  5. sylvaing

    sylvaing Active Member

    Joined:
    Jul 15, 2023
    840
    355
    0
    Location:
    Canada
    Vehicle:
    2017 Prius Prime
    Model:
    Plug-in Base
    Personally, I would try this first to see if the brake fluid needs changing.

    https://a.co/d/bgtXavP

    If not, leave it alone, but do service the brake pads.
     
  6. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,604
    38,179
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    I’ll dig up what the repair manual says in a bit.

    ^ I would just baste fluid out, directly at the reservoir, and refill. Be careful not to let fluid level get too low, introduce air into system (on Gen 3 at least that’s nigh impossible).

    FWIW Gen 3 info is in my signature. On a phone turn it landscape to see signatures.
     
    #26 Mendel Leisk, Apr 1, 2024
    Last edited: Apr 1, 2024
  7. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,604
    38,179
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Here we go:
     

    Attached Files:

  8. ZipZap

    ZipZap New Member

    Joined:
    Jan 7, 2024
    7
    2
    0
    Location:
    Oregon
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    Thanks! I'll take a look at what you sent.
     
    Mendel Leisk likes this.
  9. Zed Ruhlen

    Zed Ruhlen Active Member

    Joined:
    Sep 2, 2018
    231
    124
    0
    Location:
    Hood River, OR
    Vehicle:
    2018 Prius Prime
    Model:
    Prime Plus
    Previous car was a Nissan Leaf. They require brake fluid replacement every 2 years. I had a lease and was required to pay for it in the lease terms. This was in the USA. They had some asinine argument that the brakes aren't used as much so get contaminated "some way" which just shows that not everyone who writes service manuals is an engineer. But I wouldn't change brake fluid until I got new brakes and then I'd flush the system. There's literally no point otherwise. Unless you ride the brakes all the time. Then you probably are damaging the fluid.
     
    BiomedO1 likes this.
  10. BiomedO1

    BiomedO1 Senior Member

    Joined:
    Mar 27, 2021
    1,300
    712
    0
    Location:
    SacTown, Ca
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    You can litmus and hydro test the brake fluid to see if it's still good.
    I've had 15 year old car that the brake fluid was never changed - indicated by the sludge at the bottom of the reservoir. Clean out and flush the entire system, the car would stop in half the distance it used to. Pads and shoe changes if needed - inspection done while flushing out the system.