Brake Pedal Fade

Discussion in 'Domestics' started by bp042665, Mar 17, 2017.

  1. bp042665

    bp042665 hunting nut

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    MAKE:Jeep
    MODEL:Wrangler Unlimited X Mail Vehicle
    YEAR:2009
    MILES:233,429
    ENGINE:3.8 L V6
    DESCRIBE ISSUE.... Customer Replaced Master Cylinder ABS Module And Pump Assembly Brake Pedal Drops To The Floor
     
  2. kev2

    kev2 wrench

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    I would ask why did we replace all those components? History may help explain.

    I am checking but I believe bleeding requires a scanner - Esp that ABS module.
    There are NO codes - will need to chek as some codes may not set CEL, ABS codes may not allow ABS bleeding.
     
  3. kev2

    kev2 wrench

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    Sorry BP I dbl checked & my info says a Scanner needed to bleed ABS portion.
     
  4. NickD

    NickD wrench

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    More problems, use to be able to hot wire the ABS pump for good bleeding, now you need a scanner to do the same thing. New ones are crap, use to get 10 pulses per second now more like one.

    If your low pedal pumps up, have excessive pad gap, if not, you have air. Sure had problems with my Cruze, rear disc calipers would not adjust, GM didn't know you have to work the parking brake to do this, was a battle, wanted to replace new calipers myself, said no, would have put a stick on the pedal so it wouldn't run dry. Also refused to use their 5,600 buck scanner to activate the pump, left me with a very low brake pedal, even though the shop manual said this is the only way.

    All I could do was to vacuum bleed, drive the car to 8 mph to activate the pump, did this three or four times and vacuum bleed, after repeated this five times, finally go a full pedal. Shop manual also said to only activate the pump with a scanner for short periods of time or you will burn out the motor, but this is the law made by congress that don't even know how to open a hood.

    Had to replace all the rubber in my 88 Supra brakes, was 28 years old, could hot wire the pump and was done in minutes.

    When vacuum bleeding, remove the bleeders, clean and coat with Permatex non-hardening gasket maker, this way you are sucking fluid and not air through the bleeders.
     
  5. jd

    jd Hero Member

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    Hey Nick! That's a great tip!!! I've thought of NeverSeez or something like that, try to be able to loosen the bleeders "next time."

    I've capped the brake lines while I replaced calipers on vehicles. Found that if I did that, and didn't let the master cylinder go "dry" I could pedal bleed and not have ABS issues.

    Agree it's a pain to need a Scanner to do a simple task we've been able to do ourselves for years. Just not recently...
     
  6. kev2

    kev2 wrench

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    BP what is status - are you still working this ?
     
  7. bp042665

    bp042665 hunting nut

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    yes still playing with it the pedal would drop to floor so they replaced master cylinder still did it replaced abs assembly i have reprogramed the abs pump and did full system bleed with scanner and power bleeder . it will stop but the pedal is down at the floor blocked off all calipers and still at the floor
     
  8. billr

    billr wrench Staff Member

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    Work from the other end, put plugs in the ports right at the master and see if the pedal is nice-and-hard, should have very little travel. That would give a definite "yea or nay" on the MC. After that, I would then connect, and bleed, lines to the MC one-at-time; but this being ABS that may be useless. I can't help any with ABS, if I ever have to fix one, I will probably rip out the ABS...
     
  9. nickb2

    nickb2 Wrench. I help when I can

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    Sorry, late to this thread. Are you sure you have no brake fluid seepage? There was a recall for this on wranglers of this era.

    See snapshot. Screenshot (62).png
     
  10. nickb2

    nickb2 Wrench. I help when I can

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    It could be a pin size hole and seepage minimal but air may find a way in. Anyway, just trying to give some thoughts.
     
  11. bp042665

    bp042665 hunting nut

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    Bill i did put plugs in master cylinder ports and a good firm pedal
     
  12. Mobile Dan

    Mobile Dan wrench

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    Is that a used ABS assembly that was installed?
     
  13. bp042665

    bp042665 hunting nut

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    No Dan New From Dealer
     
  14. jd

    jd Hero Member

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    Probably done, but are all the Flexible Hoses good? I'd hate to think one was swelling up and dissipating the brake application pressure...
     
  15. kev2

    kev2 wrench

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    I did say I did not want to learn this system - I am a fool and looked into it anyway.
    Rube Goldberg on steroids.
    There are also ESC, and adjustable brake pedals options for this vehicle - any apply?
    Any indicator's on?

    The scanner may need to request DTC's from modules - B, C, U etc.
    pedal is low - will pumping raise pedal height?
     

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