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Brake question.

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by Dieselmh, May 14, 2001.

  1. Dieselmh

    Dieselmh 1/2 ton status

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    First a little background. I have a 1970 K5, which is not my daily driver. It gets driven about once, maybe twice a week. I was driving it two weeks ago and noticed that my brake light on my dash came on. When I got home, I checked, and my brake fluid was a little low. I filled it up and drove around the house a little, and the light never came back on. I went to Hawaii on vacation last week, and just got back yesterday, I fired up the blazer and did my normal pre-ride checks, and found that my brake lights don't work now. They worked before I drove it the last time. Could this problem be related to the dummy light? I checked fuses and bulbs (the easy checks) first, and they are fine. Any ideas? Thanks.

    Diesel
    [​IMG]
    Who says that size doesn't matter?
     
  2. JST12

    JST12 1/2 ton status

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    Dieselmh,
    If I'm not wrong, the dummy light on the dash comes from the brake pressure switch (tan wire by master cylinder on proportioning valve block). The rear brake lights come from a switch mounted by steering column under dash which is triggered by brake pedal position. Try manually pressing the button behind the brake pedal lever and see if the lights come on. I'm wondering if your pedal was getting low before you added fluid, and somehow broke or moved the brake light switch so it is now not activating. Of course I could be totally off base. JT

    <P ID="edit"><FONT SIZE=-1>Edited by JST12 on 05/14/01 12:34 PM (server time).</FONT></P>
     
  3. Klef72K5

    Klef72K5 1/2 ton status

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    Do you have turn signals? How about 4 way flashers?

    <A target="_blank" HREF=http://wsphotofews.excite.com/031/rw/Jo/og/t488200.jpg>http://wsphotofews.excite.com/031/rw/Jo/og/t488200.jpg</A>
     
  4. R72K5

    R72K5 Banned

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    Sounds like two problems at once. Run a tester at the brake light switch,a nd see if the orange wire is hot all the time.ANd also check to see that when the plunger of the switch is extended that the other wire becomes hot., if so then you have a problem with the harness along the frame to the rear, or a problem in the rear, with bad ground connection, a wire grounding out, or a broken wire somewhere, etc..

    The brake,s sounds like a line is broken, air getitng in your lines. Or master cylinder died on you.
    Does the pedal sink very slowly to the floor when you lay on it solidly ?
    Youve probably got a broken front hose, or broken/rusted out rear steel line

    '72 K-5 4x4, CST, 3.07, 4 speed, NP 205, 31' x 10.5", Olive green and primer, rusted out, rice smasher!
     
  5. Steve_Chin

    Steve_Chin 1/2 ton status

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    ...or a leaky seal in a caliper or wheel cylinder...

    Check for leaks. Bleed the brakes. Continue to check for leaks until you find the leak. Replace/repair the leaky part (might be a good idea to freshen up all of the seals in the braking system).
     
  6. Dieselmh

    Dieselmh 1/2 ton status

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    Yes, my blinkers and hazards work just fine. My brakes work OK, they were just a little low on fluid, they don't seem to be leaking. I haven't checked the switch under the dash yet, I'll try it this weekend. Thanks for the help.

    Diesel
    [​IMG]
    Who says that size doesn't matter?
     

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