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Help, brake light coming on

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Mudstud, Jan 24, 2002.

  1. Mudstud

    Mudstud 1/2 ton status

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    Did some pretty severe mud running this past weekend. I drive the truck home let it sit overnight and go to the car wash the next day to spray off the chasis. Everything is cool-no problems. I spray it off and then on the way home the brakes feel not quite rite and when I mash on them hard the brake light comes on and stays on until I hit the pedal again. When I hit the pedal again I can feel in the pedal a kind of pop and I can hear it too then the light goes off. I have had this trouble before after spraying the chasis down after a mud trip but all I did that time was take the rear drums off and hose the gunk outta there and it was fine. Last night I cleaned all the brake parts and did a rear brake job (it needed it). I've got better (but not normal) pedal feel now but the light still comes on when I hit them hard. I have SS brake lines and the fluid level remains full.

    Anybody have some suggestions on how to get a stripped wheel hub hex bolt out? I tried a torx bit but it spun around too.

    Mudstud
    <a target="_blank" href=http://communities.msn.com/OffroadK5s6superliftand33s.msnw?albumlist=2>http://communities.msn.com/OffroadK5s6superliftand33s.msnw?albumlist=2</a>
    76K5 6" with 33s, sb400/350/203parttime/3.73-D44/GM12bolt
     
  2. Sparky

    Sparky 1/2 ton status

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    You are probably low on break fluid and need a good bleed, or either a master cylinder is leaking or maybe a wheel cylinder. The sensor for that light gos straight to the proportining valve, and if for example your back breaks dont work well, the light turns on. Could be that you got some water in the system and thats making the breaks spongy too. Good luck.

    Sparky

    When all else fails... Check the blinker fluid.
    78 K-5
     
  3. Mudstud

    Mudstud 1/2 ton status

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    Thanks Sparky, I'll examine the master cylinder and portioning valve closely tonight. The valve is mounted on the cross member under the fan shroud right? I checked the wheel cylinders when I did the brake job- no leaky. Anybody else have any suggestions?

    Mudstud
    <a target="_blank" href=http://communities.msn.com/OffroadK5s6superliftand33s.msnw?albumlist=2>http://communities.msn.com/OffroadK5s6superliftand33s.msnw?albumlist=2</a>
    76K5 6" with 33s, sb400/350/203parttime/3.73-D44/GM12bolt
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Sounds to me like the proportioning valve is working correctly, if it is indicating a fault.

    I'd probably say Master Cylinder if your brakes are spongy.

    I thought a drum brake rebuild in the back was the excuse everyone is looking for to go disk? : )

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  5. GMCLegacy

    GMCLegacy 1/2 ton status

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    try adjusting out your rear drums. this has solved my brake light issues before. if your drums arent adjusted all the way out, it will cause a spongy pedel since the rear drums take more juice compared to your calipers.
     
  6. Mudstud

    Mudstud 1/2 ton status

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    I thought the same thing but I had to adjust the star wheel almost all the way in to get the drums on and then I did the ol' back up and lockem up trick to complete the adjustment. Last night was cold and I wasn't up to gettin under the truck but I think the first thing is to try and bleed them. Keep in mind this started before the brake job and after I pressure washed the chasis. Man, the right brake assembly was MUD-DY before I changed them out.

    Mudstud
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    76K5 6" with 33s, sb400/350/203parttime/3.73-D44/GM12bolt
     
  7. Twiz

    Twiz 1/2 ton status

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    The porp-valve will turn on the Red Brake Warring light on when it "senses" a pressure differnce, between the front and rear brakes.

    Possible causes:
    - leaking brake lines
    - leaking hoses
    - leaking fittings
    - leaking wheel cyl.&lt; (possibly the R.R.)
    - leaking calipers
    - air in the sys.
    - A faultly master cyl would also turn the RBW light on

    Also, check the rear axle seals for leaks. before the new shoes get saturated.

    <font color=white>.</font color=white>Eric
    <font color=white>.</font color=white>Twizted
     

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