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C1252 and C1256 - errors sometimes

Discussion in 'Gen 2 Prius Main Forum' started by Michciu94, Aug 30, 2022.

  1. Michciu94

    Michciu94 Junior Member

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    Hello.

    I’ve got yesterday a blinking icons and beep sound + hard brake pedal. It was for about 200m and then it dissapers and everything works fine. After one day the situation repeat. For example today I drive about 30km and no problem.

    I borrow a cable from friend and there was error C1252 and C1256 in memory.

    I’ve checked inverter pump and water flows, the wheel sensor show speed currently.

    I know that in the worst scenario it is broken ABS Pump but maybe I can do something before that? I’ve read about calibration with Techstream - can it help?

    I’ve add that I have changed rear disc and brake pads about 2 months ago and one of calliper poop out becouse I’ve push brake without pads but I’ve pushed it - some of fluid came out but it still was good level near to max in tank.

    How can I perform calibration and can something go wrong there?
     
    #1 Michciu94, Aug 30, 2022
  2. bisco

    bisco cookie crumbler

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    iirc, sometimes fresh brake fluid can help
     
    #2 bisco, Aug 30, 2022
  3. Michciu94

    Michciu94 Junior Member

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    It’s cheap option and worth to do, I will try for sure if maybe something else don’t help?
     
    #3 Michciu94, Aug 30, 2022
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  4. bisco

    bisco cookie crumbler

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    #4 bisco, Aug 30, 2022
  5. ChapmanF

    ChapmanF Senior Member

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    The two codes you have are both from the brake system, and they are related. The C1256 means that the brake fluid pressure isn't being maintained at the proper pressure, and the C1252 means the was running longer than it should have to, trying to keep the fluid pressure up. So it is not very surprising to see those two codes together.

    Ordinarily, that would be a fairly positive sign of a problem with the actuator (in a Gen 2, the actuator includes the pump and accumulator, so there's no need for any more hairsplitting over what to replace), unless you find an electrical problem preventing the pump from running, or something simple like that.

    In this case, given the mishap with the rear brake, if the system was not refilled with fluid and properly bled of air using the computer-based built-in procedure to do so, I would at least give that a shot, before spending money on an actuator.
     
    #5 ChapmanF, Aug 30, 2022
  6. Michciu94

    Michciu94 Junior Member

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    Ive got Techstream and tried to do Linear Valve Calibration and I’ve got C1345 and C1368 errors :( I’ve tried at ignition, at Ready and all time it fails - I’ve hear that ABS Pump is running. Every time I’ve hit solid icons - not flashing. Air bleed can help or i need to look for new pump?
     
    #6 Michciu94, Aug 31, 2022
  7. ChapmanF

    ChapmanF Senior Member

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    Do make sure it has all been properly bled first. It's not going to learn a proper linear valve offset if the valve is spitting air bubbles.
     
    #7 ChapmanF, Aug 31, 2022
  8. Michciu94

    Michciu94 Junior Member

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    Can you send me a Techstream procedure to air bleed?
     
    #8 Michciu94, Aug 31, 2022
  9. alftoy

    alftoy Senior Member

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    #9 alftoy, Aug 31, 2022
    Last edited: Aug 31, 2022
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  10. Michciu94

    Michciu94 Junior Member

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    Thank you. Someone have idea what more I can do before replace actuator?
     
    #10 Michciu94, Sep 1, 2022
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