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Brake light stays on...? why?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dasanii19, Dec 3, 2006.

  1. dasanii19

    dasanii19 1/2 ton status

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    I know there has to be a few reasons as to why my brake light gauge stays on, Id like to have an "elimination list" if possible? any suggestions?

    My emergency brake is not on :D
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    The light in the dash will come one if the e-brake is on or if there is a failure somewhere in the hydraulic brake system. Start with checking the fluid level in the MC.
     
  3. dasanii19

    dasanii19 1/2 ton status

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    Well the fluid is fine from what I can see. One thing I do notice is that the brake pedal goes pretty far towards the floor board before it starts to slow the truck down. Maybe the brakes arent bled? woud that have anything to do with the brake light being on?
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Most definately, now go bleed your brakes. The only reason they would need bleeding though is if you have been into them for some reason and didn't bleed all the air out or if you have a leak somewhere or the MC is bad.
     
  5. dasanii19

    dasanii19 1/2 ton status

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    Thanks, Yea I dont know what the guy did before me. Ill inspect the brakes and definitely bleed them and see what happens
     
  6. imiceman44

    imiceman44 1 ton status

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    After you bleed them check the Proportionning valve, it might need to be reset, that also will keep the light on, I had that in my 73 for a long time before I learned how it works.
    :D
     
  7. hunterguy86

    hunterguy86 1/2 ton status

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    I had that problem in my 86 k5 after I had a brake line ripped off. I repaired the line and bled all the brakes. I still had the light at the dash. All I had to do was reset the proportioning valve. This is located on the back of the front cross member usually. There is a button on the left side of the prop valve that you can press. Push that button and should be problem solved.
     
  8. dasanii19

    dasanii19 1/2 ton status

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    spectaclular advice!! Thanks guys!!
     
  9. AZ79K5Project

    AZ79K5Project 1/2 ton status

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    What you talking about Willis???? Please expand on this.. What do you mean "reset" the valve?

    I don't think you mean hitting it with a BFH...I've tried that and my brakes still don't work:haha:

    I just did an axle swap, bled the brakes and cannot get brake pressure. It sounded like large amounts of air got into the lines and up into the proportioning valve when the front lines were open during the swap and braided line replacement.
     
  10. imiceman44

    imiceman44 1 ton status

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    There is a small button, if you want, it's actually the rod for the valve itself, it sticks out at the end of the module and you push it back in with your FINGER. :D
    If you have a lot of air, in the system, you might need to check it often and reset it until you are done.
     
  11. dasanii19

    dasanii19 1/2 ton status

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    Bleeding the brakes is pretty easy right? all I do is pump or step on the brake while another guy cracks the beeder open right?
     
  12. AZ79K5Project

    AZ79K5Project 1/2 ton status

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    That generally works unless you mess up and let the MC go too low and introduce air from the top....:doah:I think that happened to me when I had the front lifted pretty high during the latest work.

    When bleeding, start with the right rear, left rear, then right front and then left front. I bought one of those $20.00 hand vacuume pumps a few years back and did a one man brake bleed everytime I've done brakes. It's also not too bad of a way to flush the system.

    I'm making a one man bleed pressure system with a tank sprayer and fittings. There are a lot of write-ups on Google and here with different creations.
     
  13. imiceman44

    imiceman44 1 ton status

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    The best way I found was gravity bleed.
    I use a clear hose on all the nipples and I open them all up, and put the hose ends in a can to recover the fluid (easier than cleaning it off the ground.
    Sometimes it take a push of the pedal to start the fluid going.
    This way I found doesn't trigger the valve, it clears all the air and doesn't foam the fluid so you don't get air after a day.
    And keeps you calipers clean.
    :D You look at the hose and you can tell when there is no more bubles coming out then you can start closing them starting from the back working your way to the front.
    :D
     
  14. onetonbb74

    onetonbb74 1/2 ton status

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    I could have swore that the rear driver is the farthest from the master cylinder, The main line goes down the passenger side and then hits the rear axle splitter, the longer line off of the rear splitter is the farthest from the master which is driver side.
     
  15. imiceman44

    imiceman44 1 ton status

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    If you do rear first either side will be the same, the split is on the center at the diff.
    :D
     
  16. AZ79K5Project

    AZ79K5Project 1/2 ton status

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    Gravity Assist

    I made a pressure bleeder. Cost was about $20.00. I use the compressor set to about 5 to 10 PSI. I got constant pressure at all four wheels and was done in about 10 or 15 minutes from the time I bolted the new MC on.

    P1010587 (Large).JPG

    I added a valve stem to remove excess air from the line.


    P1010589 (Large).JPG

    Loaded the tank with a bottle of brake fluid - MC never goes dry.
    P1010583 (Large).JPG

    UPDATE: I replaced the 16 gauge top plate with 3/16" inch metal with a rubber tool drawer liner as a gasket. I was getting too much leakage with 16 gauge metal.

    P1010585 (Large).JPG

    P1010586 (Large).JPG

    P1010587 (Large).JPG

    P1010583 (Large).JPG

    P1010585 (Large).JPG

    P1010586 (Large).JPG

    P1010589 (Large).JPG
     
    Last edited: Apr 9, 2008
  17. dasanii19

    dasanii19 1/2 ton status

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    Pretty slick man, ill have to try that sometime for sure. Thanks for the post
     
  18. Thunder

    Thunder 3/4 ton status

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    Your master cylinder may be going bad. That will also set off the brake light.If you have not opened up the brake system without bleeding it and dont have any leaks. And your brake pedal has got worse and goes down further and further over time it could be the master cylinder.
     
  19. 88-383

    88-383 1/2 ton status

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    I use a suction bleeder, it has an adapter that attaches to my compressor so it can pull fluid. It works great, but you have to keep the resovoir filled so it doesn't go empty.

    KM
     
  20. AZ79K5Project

    AZ79K5Project 1/2 ton status

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    You may already be doing this...Take the top off from the brake fluid bottle and place the brake fluid bottle upside down over the resevoir that is being drained. It will autofill the resevoir as you bleed the brakes.

    I picked up a suction bleeder from Harbor Freight that had the refill bottle for that purpose. The worked for 5 minutes and broke around the air hose fitting.
    Harbor Freight Bleeder
     

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