1992 GMC c1500 - Emergancy Brake light in dash always on

Discussion in 'GMC Truck Forum' started by chrismclaws, Apr 8, 2011.

  1. chrismclaws

    chrismclaws Member

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    I have a 1992 GMC 1500c truck and the light in the dash for the emergency brake is always on.
    If I lock the emergency brake down the light goes brighter,
    and then when I unlock the emergency brake the light is not as bright but is on.
    Is there a switch like on the brake petal that turns on and off that light?
    If so what is it called?
     
    Last edited by a moderator: Apr 9, 2011
  2. zombie1969

    zombie1969 Senior Member

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    If the wire to the ebrake is shorting someplace its a matter of tracing the short.But that same light should be for the main brakes also so if you have a problem with leaking lines or air in the system the light will come on and you might have a low fluid levle sensor on the master telling you the fluid is low and the brakes need service.
     
  3. c15004ever

    c15004ever Senior Member

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    i have the same problem, there doesn't seem to be anything wrong with my brakes; fluid level is fine. Where does the wire for the e-brake run from and where does it run to?
     
  4. crabtruck

    crabtruck Senior Member

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    The dash light in those years typically serves 3 purposes.
    You may notice an ABS label nearby, use varies.
    In some truck setups the ABS light functions independently,
    and in some it does not have it's own bulb.
    Depends greatly on whether you have ABS or RWAL.
    ABS is 4 wheel antilock and RWAL is 2 (rear) wheel antilock.
    There is a third type but not used on 1500's.

    This link will show basic difference between ABS and RWAL looks:
    http://www.truckforum.org/forums/gm...rake-warning-light-goes-35-mph.html#post53328
    RWAL in thumb has simple pipes, ABS link is many pipes.

    A brake pressure problem or an antilock problem will turn on dash light.
    Neither will cause dash light to be as bright as using E-brake.

    E-brake causing light to brighten and dim suggests not a problem.
    There are ways for problems involving weird shorts etc,
    but first you should troubleshoot as if system is working properly.

    Directly out of master cylinder, the two pipes head to 'combo valve'
    which protects from total brake failure as one of it's jobs
    by reacting to broken lines and leaking wheel cylinders.
    There is a single wire attached to the top of it which lights dash.
    Unplug this wire. If dash light goes out problem is this direction.
    Could be as simple as the valve is not centered or pressure problems.

    If dash lamp is still on, leave unplugged and unplug harness to
    either ABS or RWAL, whichever you have.
    Do this at 'brain box' not at little valves.
    If dash lamp goes out problem is antilock related.

    If lamp is not out with combo and antilock unplugged,
    and of course, E-brake released, you have a wiring problem.

    Do let us know if you have RWAL(likely) or ABS(mostly 'burbs)

    c15004ever it appears you have an RWAL setup.
     
  5. 87c10slammer

    87c10slammer Senior Member

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    my 92 does the same thing.. brakes have always worked fine.. my abs light comes on and off periodically when i hit a bump as well.. i tried tracing down the problem but ended up doing the ole electical tape trick..
     
  6. NSguy

    NSguy Senior Member

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    Mine does the same thing. I found out that it doesn't 'go up' all the way, so I bungee corded it to the grove in the plastic above my fuse panel. It's worked since.
     
  7. chrismclaws

    chrismclaws Member

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    Thanks for all the info, it's a RWAL. Will be looking into this, now I know were to start.
     
  8. chrismclaws

    chrismclaws Member

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    It was the ABS that was keeping the light on. Thanks for all your help.
     
  9. shadygrady

    shadygrady Senior Member

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    Question crabtruck.On the RWAL setup my light goes out when I disconnect the single wire that connects on top next to the brain box.the wires go into the same loom as the black boxes wires.What is this called or what needs replacing.Does the combo valve off to the passenger side of fluid reservoir need replacing or what?I havent had to deal with ABS issues in past so im not sure what to do next.
    I am having a lot of shuddering on stopping like the abs is grabbing really hard and releasing.I realize it could be the rotors but they look fine when visibly checked with a straight edge.They could still be the problem but with my brake light on and everything else normal I just want to eliminate all possibilities before replacing parts,thanks.
     
  10. chevychase

    chevychase Senior Moderator Staff Member

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    Will try and help some.. Abs light is on? Maybe a sensor . But try this .. pull abs fuse see if it stops pulsating. If it does you need to have it scanned.
    If it persist after fuse pulled need to check rotors ect. I would go to a open parking lot and try this for safety ... brakes will work but for safety.
     

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