Brake Booster Accumulator Actuator issue?

Discussion in 'Gen 2 Prius Technical Discussion' started by Renee Thomas, Sep 22, 2021.

  1. ChapmanF

    ChapmanF Senior Member

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    A Gen 3 owner faces more of a puzzle because they split that stuff up into two units, so a Gen 3 owner has to make the call which one has to be replaced (or just do both, double ugh).

    [​IMG]

    As a Gen 2 owner, you do not face that difficulty. There's just the one big combined unit.
     
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  2. Renee Thomas

    Renee Thomas Junior Member

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    And here is a Gen 2 Prius making a similar sound. Sounds much like mine. It's entertaining to read the comments. Everyone was very clueless years ago.

    And this video - shows the codes. I never had codes (the dreaded
     
  3. Renee Thomas

    Renee Thomas Junior Member

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    Wow! I just watched the video above on the replacement of the ABS Actuator. Definitely quite involved. I need a lot of faith in my mechanic!
     
  4. koco

    koco Member

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    After watching the video of your car making the motor buzzing sound accompanied by the knocking sound in the back, I would say for sure you need a replacement ABS actuator. My car had the exact same issue, and was resolved after actuator replacement.

    The knocking sound in the back is not Domino's Pizza Delivery; I'm not sure what component it is, but it went away when the actuator was replaced. I got a used part for $200 with a 6 month warranty. It is the labor that is the big part of it. It's not really terrible, and it takes about 3 to 4 hours.

    The Toyota Techstream software was not really complicated and did kind of display the steps needed. It was a one person bleed procedure using a stick to jam between the seat and brake pedal to hold it down when needed.
     
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  5. Renee Thomas

    Renee Thomas Junior Member

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    I'm always impressed with people who can handle this type of repair on their own. It's going to cost me about $2350 for a new one to be installed in Orlando. It would have been a few hundred less in Tampa but I didn't feel confident driving two hours, then waiting all day, and driving back. And, of course, there's always the chance of a delay, then I'd be stuck in Tampa. So, I'll get it fixed locally and be done with it. I think I deserve a Domino's Pizza delivery after this!
     
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  6. Renee Thomas

    Renee Thomas Junior Member

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    @ChapmanF @jerrymildred @koco
    Update: My 2009 Gen 2 Prius is sitting at Dynasty Automotive awaiting replacement of the brake booster/accumulator/actuator. The part was ordered today from Toyota, and the replacement will be tomorrow. They ran a diagnostic today after bleeding the brakes (at my request, and at no charge by the way) and this image attached shows the dreaded C1256 code. (I covered my VIN in the image, but I confirmed it is my VIN.) In the "Tekmetric" inspection report they sent to me, it says, "Check engine light on. P1116 & C1256. Heater control valve and ABS module need to be replaced. The code is present but has not initiated the ABS light to turn on as of yet. Brake system was bled per request but ABS module still losing pressure internally and turning on the pump which is what the customer is hearing. ABS module needs to be replaced." Total cost should be $2,259.28 (labor 4.5 hrs, $445.50; ABS module $1,675.89, plus $137.89 tax - ouch!). Or maybe the total is $2,303.72 with some other fee. Regardless....it is what it is! Prius C1256-VIN blocked.png
     
    #66 Renee Thomas, Oct 14, 2021
    Last edited: Oct 14, 2021
  7. jerrymildred

    jerrymildred Senior Member

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    The P1116 is for the "thermos" that stores warm engine coolant. It can be the valve but usually, the valve would throw its own code. That particular code they got means the coolant temperature at the valve isn't what was expected. Changing the temperature sensor fixed it on my wife's old 2007 Prius. Easy to do once you get the tupperware out of the way. You can access it from underneath after pulling off a couple of the splash shields under the front left corner of the car.

    The B1421, if you didn't already know it, just means that the car is in the shade. Not a problem.
     
  8. Renee Thomas

    Renee Thomas Junior Member

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    Thank you very much for the response. Maybe the P1121 is the code thrown when the valve is bad? I haven't seen that code in the last few weeks but plenty of times in the past 6 years along with the P1116 code. I even have notes on how to replace the part but never really thought seriously about doing it since it's not terribly important. And regarding the B1421 code, thank you for the explanation. I was about to research that next, so you saved me an effort! Thanks!
     
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  9. ChapmanF

    ChapmanF Senior Member

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    Depending on just which way that valve gets stuck, you could find yourself without cabin heat at some point.

    That might not be a big deal in Orlando. Indiana will have some days where that matters....
     
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  10. Renee Thomas

    Renee Thomas Junior Member

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    I'm happy to report the repair is done - my 2009 Prius (Gen 2) has a new ABS Modulator valve/brake booster/accumulator/actuator (how many names does this thing have? lol). $2,303 total cost. The ABS module alone was $1,675. I see OEM replacements online for much less, too bad I don't have a "personal mechanic." Anyway, it is done and installed by a very reputable place. No issues occurred during the surgery. The patient has recovered and all previous buzzing, thumping, and brake "barking" symptoms are gone.
     
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  11. ChapmanF

    ChapmanF Senior Member

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  12. koco

    koco Member

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    Good news! How often does the ABS pump run now that it is renewed?
     
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  13. Renee Thomas

    Renee Thomas Junior Member

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    I haven't hardly heard a sound out of my car in a few days now! Maybe a tiny buzz here and there, pretty faint. I think it's the "normal" occasional buzz. The brakes are very quiet!
     
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  14. jerrymildred

    jerrymildred Senior Member

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    Sounds great. It's normal for the pump to buzz for a few seconds when you open the driver's door to get in and then occasionally as you drive (usually while stopped with foot on brake pedal). As the brakes get used, pressure drops off and the pump needs to recharge the system.
     
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  15. Renee Thomas

    Renee Thomas Junior Member

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    Thanks. I do hear an occasional buzz.
     
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  16. koco

    koco Member

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    I have noticed that a lot of these failures occur on Florida cars, so maybe the high humidity contributes to moisture in the brake fluid leading to corrosion within the actuator. Much of Florida has more than 80 percent humidity for much of the year. Hmm
     
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  17. jerrymildred

    jerrymildred Senior Member

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    Interesting theory. If so, then regular brake fluid replacement ought to help preserve the life of the pump. I had mine replace on my Prime at 30k. Planning for the same on my wife's Prius at the same mileage, although she's not accumulating the miles as quickly as I am.
     
  18. koco

    koco Member

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    Also, I performed the service manual resistance testing on a failing ABS accumulator and it passed; all the readings were within specs. This probably means that a seal or other mechanical component was failing which would make sense if the failure was due to corrosion. The fluid in this one was really dirty and old.

    I could not find a bench test for the mechanical parts and it would probably be really involved if there was such a thing.
     
  19. Renee Thomas

    Renee Thomas Junior Member

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    @jerrymildred @koco

    Regarding a failing seal or other mechanical component within a failing brake booster, the technician who changed mine out told me the day I dropped off my Prius that he once took a bad one apart and he could see a bad "seal" or "diaphragm" and he said he wondered if just that one part could be replaced. I half-jokingly told him that I wanted to see what my booster looked like inside to see if there really was a torn or tearing diaphragm to help justify the expensive repair. But I didn't follow-up on asking for that, and I didn't even think about it again. I was just so happy to get my car, I drove off the lot not even thinking about it. Is

    it safe to say that with my new brake booster that I also have new brake fluid? If so, I'll make a note to change my brake fluid in 30,000 miles (it's at 97,000 miles right now). If not, I'll get it done right away! I would assume my Prius has new brake fluid since they needed to bleed the brakes as part of the brake booster replacement....but I'd like confirmation on that! Thanks!
     
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  20. koco

    koco Member

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    I had to put in over 1 quart of fluid along with the actuator change. Whether or not all of the fluid has been renewed is another story. The fluid that was coming out of the bleeders at the end of the bleed procedure was clean looking. I plan to flush the fluid again within a few months.
     
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