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Brake system help needed

Discussion in 'Generation 1 Prius Discussion' started by Greenacarina, Jun 8, 2023.

  1. Greenacarina

    Greenacarina Junior Member

    Joined:
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    Arlington, wa
    Vehicle:
    2003 Prius
    Model:
    ----USA----
    Hello!
    So, I am finally trying to fix my poor 03 Prius!
    Learning that the entire cowl piece comes out was a game changer....but now I am left with a few questions.
    I believe my brake actuator is what crapped out, based on the codes I got and subsequent advice I received here. I am looking at the component on the passenger side...still not sure what to call the associated brake component that is closer to the driver's side (the one that has all the brake lines attached and appears to have multiple solenoids?)
    Anyway, I realize these were problematic from day 1 and there was some kind of recall (that I am years late for).
    So, here I am, wanting to replace this with a good used part (new one is well over $1000)...how can I tell (part number or physical appearance?) if the used part I am getting is "pre-recall" or "post-recall"?
    Obviously don't want to replace my dead unit with something that will also likely fail.
    Also, not knowing how this thing works, or what fails internally, is it possibly to repair what I have??

    Thanks much
    Chris
    Screenshot_20230608-111823_eBay.jpg Screenshot_20230608-111553_eBay.jpg
     
    #1 Greenacarina, Jun 8, 2023
  2. ChapmanF

    ChapmanF Senior Member

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    You're not sure what to call the one closer to the driver's side, because you've used its name for the other thing. :)

    The thing you're looking at on the passenger side is the "power supply portion" (in later generations we just call it the pump and accumulator). The thing that's closer to the driver with all the lines and solenoids is the actuator. The thing even closer to the driver with the pedal attached is the master cylinder/booster.

    [​IMG]

    Maybe you're thinking of some service campaigns that get widely discussed for later generations?

    I've never been aware of a recall or campaign on these components in a Gen 1 (but then, it's been several years since I had my Gen 1). On the other hand, any Gen 1 is a pretty old car by now, and it isn't shocking that anything might wear out.
     
    #2 ChapmanF, Jun 8, 2023
  3. Greenacarina

    Greenacarina Junior Member

    Joined:
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    Location:
    Arlington, wa
    Vehicle:
    2003 Prius
    Model:
    ----USA----
    Ok, so it seems that I need the hydraulic booster. Went through the test procedures in the manual and the pump motor in this unit does nothing when I apply power to the appropriate terminals (bm1/bm2 and gnd1/gnd2)
    Is this booster unit only available as a complete assembly, or is the pump motor something that can be replaced on it's own??

    Thanks
    Chris
     
    #3 Greenacarina, Jul 3, 2023
  4. ChapmanF

    ChapmanF Senior Member

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    You have to be extra extra careful with the names for these things, because if you look in the drawing posted above in #2, you see there are two different things with Hydraulic Brake Booster in the name. The "power supply portion" is the assembly it sounds like you're looking at, and the "master cylinder portion" is the one nearer the driver. (It gets a little clearer in later generations, where instead of "power supply portion" it's just called the pump and accumulator. The actual "booster" is just a small chamber machined into the back of the master cylinder.)

    I think Toyota only sells the "power supply portion" (a/k/a pump/accumulator) a an assembly.
     
    #4 ChapmanF, Jul 4, 2023
  5. ArCanSawDave

    ArCanSawDave New Member

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    Location:
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    Vehicle:
    2003 Prius
    Model:
    SE
    I repaired the booster assembly in my 2003 Prius. I found that the electric motor in my booster assembly wasn't running. I bought my Prius from a friend that parked it for four years after it had some problems. Upon disassembly I found that the commutator bars were severely worn on the armature assembly. I found a kit on eBay that consisted of a replacement armature and new brushes for about $159. I believe the armature assembly i bought was actually for a early to mid 2000s Toyota 4runner/Lexus GX470, but it's been working fine now for approximately 23k miles. I believe they use the same assembly for the abs pump.
     
    #5 ArCanSawDave, Aug 30, 2023
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