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Brake light

Discussion in 'The Garage' started by Chrisblazzer89, Nov 16, 2006.

  1. Chrisblazzer89

    Chrisblazzer89 1/2 ton status

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    Ok i need some help my brake light in the dash keeps coming on wen i drive but my brakes work fine seem fine and i have full fluid

    any idea wat it could be that is causein the light to go on
     
  2. dremu

    dremu Officious Thread Derailer Premium Member

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    Either the parking brake is set, the pressure is wildly different front-to-rear, or the ABS computer is pissy.

    What year / flavour of truck?

    You can try resetting the combo valve by pressing the rubber dimple on it, as that's tied into the second option above. Fiddle with the parking brake and make sure the lever isn't clicked once and the switch isn't gummed up, that's #1 above, and if your truck is a 90-91, the ABS computer might make it blink.

    Oh, and #2 can happen if you have, say, a leaky wheel cylinder in the back but the fronts are okay, or a leaky caliper up front but the back's okay (but I think you'd notice this.)

    -- A
     
  3. Chrisblazzer89

    Chrisblazzer89 1/2 ton status

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    its an 88 blazer were is this combo valve?
     
  4. resurrected_jimmy

    resurrected_jimmy 1/2 ton status

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    Combo valve is right next to the master cylinder. Its a machined aluminum jigsaw puzzle looking piece.
     
  5. dremu

    dremu Officious Thread Derailer Premium Member

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    Uhh, on firstgens, yes.

    On 73+ trucks, the combo valve is on the front of crossmember below the fan. There is a rubber button usually covering the dimple, IIRC on the driver's side. Follow the brake lines from the master down and you'll find the thing.

    -- A
     
  6. Chrisblazzer89

    Chrisblazzer89 1/2 ton status

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    so wat exactly does it do wen I press it.

    And oh yea I just replaced a brake line and bled the brakes and they work perfect them like a week later the light came on .
     
  7. dremu

    dremu Officious Thread Derailer Premium Member

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    Pressing the nubbin resets the switch inside, which can get set if there is a large pressure difference between the front and rear circuits.

    Why'd you replace the line? Front or rear?

    I'd rebleed, including the valve reset, but still curious about the line.

    -- A
     
  8. Chrisblazzer89

    Chrisblazzer89 1/2 ton status

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    the line roted out at the lil bracket that goes from steel line to rubber line.
     

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