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00 K2500 Brake pedal to floor

Discussion in 'Chevy Trucks' started by Sailor77, Jul 14, 2012.

  1. Sailor77

    Sailor77 Junior Member
    from Indiana
    Messages: 8

    I have searched and read all the discussions here on these trucks and poor brakes, yet had yet to read a total solution. My 00 K2500 (7.4L) Crew cab brake's are horrible. This started several months ago when the hydroboost blew, and then lost two power steering pumps. I replaced everything, and when I lost another reman hydro boost, I swapped to vacuum assist with new booster, master cylinder and pedal. I also check the rear brakes and replaced the adjusters, cylinders and hardware. I bleed the system several times and the pedal still goes almost to floor with very little stopping power. I took it to the dealer and they did a power bleed on the system which make a huge difference, one that I could live with. However by the time I got home, about 10 miles, it was back to the floor. I went back again to have them check it over and they said "we give up!" Keep in mind all they did was bleed the brakes. So I am at a loss, I have tried pulling the ABS fuse, and even the plugs from the ABS controller with no positive effect. Oh,I also replaced all soft lines with steel braided. This has become a nightmare to where I feel unsafe drive my truck... Any ideas?
     
  2. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,973

    I'm assuming your not loosing any fluid correct?
     
  3. Sailor77

    Sailor77 Junior Member
    from Indiana
    Messages: 8

    Correct, no fluid loss.
     
  4. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,973

    Ok. That's a start
     
  5. doyles

    doyles Member
    Messages: 95

    could the master cylender be bad.
     
  6. Sailor77

    Sailor77 Junior Member
    from Indiana
    Messages: 8

    total of three master cylinders have been on truck, all with same results.
     
  7. Sailor77

    Sailor77 Junior Member
    from Indiana
    Messages: 8

    I have done more testing this morning. I first plugged both ports on Master Cylinder and the pedal was firm. I plugged only the rear and hooked up front brake line, pedal to floor. I reversed, hooking up rear and plugging of front, firm pedal. I was able to lock the rears up with a 40ft skid. This leaves three pieces, the combination valve, ABS and calipers. Yes, the calipers are original and installed correctly.
     
  8. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,973

    So....that means that the front section is the issue.
     
  9. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,973

    Try and "hot wire" the abs to get to activate
     
  10. peteo1

    peteo1 PlowSite.com Addict
    Messages: 1,660

    Probably the abs. I had a 99 that I had brake issues with. I unplugged the abs and all the problems went away.
     
  11. Sailor77

    Sailor77 Junior Member
    from Indiana
    Messages: 8

    Yes, it would appear that it is in the front system. I replaced the calipers, pads and since I already had the rotors, those too. Bled the system and same results. The only thing left is the ABS controller and combination valve. Pulling the ABS fuse, has no positive effect. How can I "hot wire" the ABS? Does anyone had a diagram of how the ABS module works or a list of ABS codes? I believe jumping A&H pins will give me any ABS codes stored in the system.
     
  12. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,973

    I was meaning hot wire to get abs to activate,,,,maybe there's air in the unit.
     
  13. Sailor77

    Sailor77 Junior Member
    from Indiana
    Messages: 8

    How would I "hot wire" the ABS pump to activate?
     
  14. doyles

    doyles Member
    Messages: 95

    i remember a friend of mine had a 1500hd chevy. he had soft brake pedal but i think he said the truck almost wont stop ,pedal to the floor and i dont remember but i think he said somthing about the abs.
    well he replaced roters,calipers,brake pads and brake lines and then replaced both front wheel bearings because thats were the abs sensor is. when he replaced the front wheel bearings problem solved.
    hope this helps
     
  15. Sailor77

    Sailor77 Junior Member
    from Indiana
    Messages: 8

    An ABS code came up today. CO235 Rear Wheel Speed Signal Circuit Open. With the scanner hooked up I could see all wheels showing 5mph in park. I cleared the code and it immediately returned. I unplugged the rear sensor and code and 5mph stayed constant. Brake pedal still goes to floor.
     
  16. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,973

    Try pulling abs fuse. Take the whole abs unit outta equation
     
  17. SHAWZER

    SHAWZER PlowSite.com Addict
    Messages: 1,152

    Curious to find out what is causing this problem? I think he said he pulled the abs fuse in his first post.tymusic:drinkup:
     
  18. Sailor77

    Sailor77 Junior Member
    from Indiana
    Messages: 8

    yes I have removed the ABS fuse with no change. I am looking to the ABS Electronic Brake Control Valve GM# 12475489. Although I am still not sure how this could be a factor with the EBCM (Electronic Brake Control Module) not working, I suppose anything is possible...in theory. I am getting a used one today and I will post results.
     
  19. csi.northcoast

    csi.northcoast Senior Member
    Messages: 320

    pulling the fuse will not work.. i had a 97 2500 did the same thing, you have to disconnect the wire to the abs unit... i think it had a blue connector ... two wire harness... it has been a while so i may be off... but that was the only thing that helps