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in-cab "brake" light

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by misfit, Jul 14, 2001.

  1. misfit

    misfit 1/2 ton status

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    in-cab \"brake\" light

    its the red light on the instrument cluster, over on the bottom left. all of a sudden came on last weekend. pedal feels a little weak too. whats this mean. btw this is on a 74
     
  2. 502Burban

    502Burban 1/2 ton status

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    Re: in-cab \"brake\" light

    That light is triggered by the proportioning valve, when it senses a difference in pressure between the front and rear systems. So you probably are leaking brake fluid somewhere in the system. Check your lines and all connections. Possibly one of the drum brake cylinders or the flex lines have spring a leak.

    Robb
    '73 GMC Suburban - 502DFI
    <A target="_blank" HREF=http://community.webshots.com/user/robbrj>http://community.webshots.com/user/robbrj</A>
     
  3. Tybee

    Tybee 1/2 ton status

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    Re: in-cab \"brake\" light

    Same thing happened to me when i broke a spring in my drivers side drum.

    Theres nothing like fiddling with my Jimmy! 1984 GMC Jimmy 379 diesel, 700R4, 3.73s, 31 x10.50 x 15
     
  4. Twiz

    Twiz 1/2 ton status

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    Re: in-cab "brake" light

    Like 502burban said, the light is triggerd by the prop valve.

    Think of the prop valve (Red Brake Warning light) as a three way switch. In the neutral postion the light is off. If one of the brake line pressures drop below the other, then the swirtch is pushed to the low side. Cutting off brake fluid to the low side and activating the R.B.W. light. So, now the problem needs to be diagnosed. It could be a fault in the front or rear brake sys. Common problems are; Leaks somewhere in the sys. Possibly low fluid levels (master sys swallowd some air). Leaking rear wheel cyl or front calipers. Leaking brake lines (steal or rubber). ETC....

    When the problem has been found and repaired. The brake sys. will need to be bled correctly, to remove the air in the sys. In some cases, the prop valve switch will want to stick in the defalt position. A clip is avalibe to depress the small button on the end of the prop valve (located on the front cross member)--- Umm, Keep us posted. and we'll go from there.

    Twiztid
     

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