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Brake Booster Pump Motor running too often and too long after replacement

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by kamrul, Nov 13, 2023.

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  1. kamrul

    kamrul Junior Member

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    I have had issues with the brake booster in my Gen 3 Prius and the details of that can be read in this post ABS, Brake and Traction lights on with codes C1252, C1253, C1256, C1365 | PriusChat

    The long story short, I had codes C1252, C1253 and C1256 hence replaced the brake booster pump motor only with a used/reconditioned unit around a month ago.

    I have never replaced the brake fluid in my 4+ years of ownership of the vehicle and I am not sure whether the previous owner replaced it either. I only topped up the brake fluid reservoir with Toyota DOT 3 as much as required during the pump motor replacement procedure.

    Recently, I noticed that the pump motor runs for a significantly longer duration than usual when the car is unlocked and the driver-side door is opened. I have also noticed that the pump motor sometimes runs every 10 seconds or so even without the brake pedal pressed.

    However, I have got the ABS and brake lights on again with beeps, scanned only to find the same following codes -

    C1252 Brake Booster Pump Motor on Time Abnormally Long
    C1253 Pump Motor Relay
    C1256 Accumulator Low Pressure

    The workshop where I had the pump motor replaced has said that there could be internal leakage in the master cylinder which is why it can't hold up the pressure resulting the pump motor running overtime. Although there is no code C1391 for abnormal leakage yet.

    Here's a video of the specimen for you, the experts on this forum for a better understanding of the issue I am describing. It shows brake pressure falling and the pump motor running without the brake pedal pressed.



    In case the video can't be seen on the PriusChat mobile app, here it is https://drive.google.com/open?id=11gbt63t0OnFVVnsFjyiNtNgcbKeYhzIX&usp=drive_fs

    Do I now need to replace the master cylinder as well?
     
    #1 kamrul, Nov 13, 2023
    Last edited: Nov 13, 2023
  2. Tombukt2

    Tombukt2 Senior Member

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    I believe you're going to find leaks usually are around the accumulator and the pump generally but yes the other part can be suspect many times if you use a mechanic stethoscope and be quiet and listen to the business on shutdown startup brake pedal depressions have someone pressing on the brakes while you're out listening in between all the racket and sometimes you can hear the leak literally and then you kind of know what component you're dealing with so as the part that does not house the pump and that high pressure accumulator is leaking as it leaks down it turns the pump back on and the vicious cycle continues or the leak could just be at the accumulator pump section and it will do the same thing That's why Toyota and lots of places want to replace both parts at the same time and those are going to be about anywhere from 12:00 to $1,800 for the two pieces together there's a wide range of pricing apparently so that's what happens I don't see why you would rebuild the accumulator pump motor only I've taken mine apart just to look at on the generation too not really much to see and the pump doesn't really go bad it's pumping away all the time you hear it It's not pumping away because it can't pump enough pressure where it's pumping the pressure to cannot hold it. So I'm not sure why I would be rebuilding the pump or the motor I'm sorry It's working just fine You hear it.
     
    #2 Tombukt2, Nov 13, 2023
    kamrul likes this.
  3. kamrul

    kamrul Junior Member

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    Both would cost $2500+ parts alone where I live, unfortunately.

    Now I am getting the check lights and the same codes every other day or two. Those are C1252, C1253 and C1256. Still no C1391 saying there is an abnormal leak in the actuator. The pump motor doesn't spin. Clear the DTC and the pump motor would run again. However, I noticed that the pump motor runs more frequently now, once every 10-15 seconds even without the brake pedal pressed.

    My mechanic has suggested me to keep driving this way till I get the code for an abnormal leak. I wonder if making the pump motor running too often like this is actually weakening it.
     
    #3 kamrul, Nov 20, 2023
  4. ChapmanF

    ChapmanF Senior Member

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    Should be hours without the brake pedal pressed, so that's already awful. There isn't anything else you're waiting for really. As for extra wear on the pump, sure, you can do the math; every day driving around like that can be like a year of normal use.
     
    #4 ChapmanF, Nov 20, 2023
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