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DIY: Brake Booster/Accumulator Troubles

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by WuTangFlan, Jan 8, 2023.

  1. WuTangFlan

    WuTangFlan New Member

    Jan 8, 2023
    Lexington, KY
    2012 Prius
    Hello Everyone,

    My laziness and cheapness (aka poorness) have gotten me stuck replacing my brake booster and accumulator and am hoping that some of you more experienced than me can maybe push me in the right direction.

    I noticed my accumulator running every 15 seconds regardless of pushing the breaks or not and could hear a hissing vacuum leak so I decided to replace the Booster and Accumulator before any warning lights appeared.

    I first bought a Used Booster/Accumulator from a local junkyard. They mentioned it was off a ct200h but their interchange said it would work (Narratror: it did not). When installed the booster was not recognized by the car at all (due to the software on the booster being different I assume, parts were physically identical, although different part #'s).

    I purchased another salvage Booster but left the accumulator from the Lexus installed (this may be a key mistake, but the accumulator didn't seem to have any differences). Verified this particular booster was the correct part # through multiple sources. Installed and hooked everything back up, connect the battery and go to start the car and I do not hear the accumulator start running to build pressure and when I start the car. I plug up my trusty counterfeit USB dongle and pirated techstream and see 2 error codes (low accumulator pressure and long pump runtime). There were never any warning lights before, so I don't know if these are previously stored codes to the booster (my worry), or if they are just from having they system apart.

    When trying to do the brake flush procedure it errors out immediately, this I believe is just due to it being a crappy dongle. I plan to purchase the Tactrix, but need to know if I have other problems going on as well.

    So basically I'm concerned that:

    1. My accumulator didn't run the first time the car was turned back on; this could be due to either the accumulator being wrong, or due to it being hooked up while an unrecognized booster was installed, or due to the codes currently in the booster (See #2).

    2. 2 codes were present in techstream. There were no warning lights before, but I didn't read codes with the techstream prior to this repair (attempt), only a generic bluetooth reader. I'm concerned that these codes were stored to the salvage ABS unit and thus the unit is bad, but they could also be valid codes that just hadn't triggered a warning yet.

    If neither of those concerns are valid then I'll go ahead and get the Tactrix, but if it's likely I (still) have a bad pump or accumulator installed then I'd rather get those addressed before getting the Tactrix.

    Anyway thanks for any input you all may have.
  2. rjparker

    rjparker Tu Humilde Sirviente

    Jun 6, 2008
    Texas Hill Country
    2012 Prius v wagon
    One way to verify the correct master cylinder is to run your car's vin against an online Toyota parts dealer. You can then determine the correct part number for your car which varies by tire size, year and Prius body style.

    You can then do the same procedure against the salvage car that is supplying the master cylinder.

    Recently another Priuschat user solved their replacement master cylinder comm problem by simply properly snapping in the orange high-voltage connector.
  3. Matt98svt

    Matt98svt Junior Member

    Aug 27, 2021
    South Carolina
    2015 Prius v wagon
    I am in the same boat with my 2013v needing the replacement as well. No codes have shown up yet for me, but I get the pump turning on about every 10-12 seconds now. The problem with finding used units for our cars is that only 2012-2014 model years used the same part number and generally cars that old are going to have 100k miles plus and I don't want to put in all the labor to replace it only for it to go bad again in a year or two. Unfortunately, the cheapest new unit I can find is around $1100 just for the brake booster assembly. I have been told the majority of leaks come from it so was going to replace it first and hope that fixes it. I purchased the thinkdiag, around $100, to handle the brake bleed process and linear valve relearn but still reading up on how to do those steps with it. I hate you are having those issues and hope it is not a scenaro where you have to pull everything out and start over again. Toyota should have replaced these parts under a recall and I encourage you to join the class action lawsuit against them regarding the brake booster issue