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Brake light on dash lights up

Discussion in 'Chevy Trucks' started by snowbankr, Apr 21, 2009.

  1. snowbankr

    snowbankr Member
    Messages: 49

    My '92 GMC 2500 4x4, 5.7 auto, 8600gvwr is giving me some trouble. Brake light in the dash comes on, there are no leaks, lines have been checked (several times daily), new rotors, pads, wheel bearing/hub assembly on both front wheels. Checked fluid level in reservoir, was/is full and isn't going down. When truck has set without engine running, brake pedal is solid after a regular push and holds steady, does not fade. Start truck, let it run for minute or two, drive down the road about mile and a half, light comes on, stays on until truck is shut off. brakes are working, can feel and hear them, pedal feels fine when engine is running. Turn truck back on, engine running, no light, then down the road, presto, like clockwork, light is on. Any ideas??

    Thanks for your help.
     
  2. mayhem

    mayhem PlowSite.com Addict
    from Peru MA
    Messages: 1,016

    Parking brake on one click?
     
  3. RAZOR

    RAZOR Senior Member
    Messages: 342

    Could there some kind of problem with the rear anti lock brakes?
     
  4. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    If it has antilock brakes the connector, sensor or wiring may have a problem. Older stuff does not have ABS warning lights. Does it have a brake fluid level sensor? Could be the differential valve sensor is not in the middle position and it's telling you that one circuit of brakes is out. Even tho it's not. It happens when you bleed brakes. It gets pushed to the weaker side
     
  5. snowbankr

    snowbankr Member
    Messages: 49

    Thanks for the ideas guys. We already unplugged the porpotioning valve next to the master cylinder, the ABS is still plugged in....will unplug that next. Got a mechanic coming to look at it on Friday. He checked wheel cylinders, pads, shoes, (rear had all new from wheel cylinder to drums in October of 08), calipers, and lines. Only thing(s) left is master cylinder, wiring, under the hood stuff, etc. It's something simple, always is...when we find it, I'll post to let you know. If anything else comes to mind, please post.

    Thanks,
    Ken
     
  6. mayhem

    mayhem PlowSite.com Addict
    from Peru MA
    Messages: 1,016

    Universal fix.

    tape2.jpg
     
  7. snowbankr

    snowbankr Member
    Messages: 49

    Too funny Mayhem. With all my old junk I run, duct tape, elect. tape and a loud radio makes old trucks new again. I have already applied the tape over the light, except my positioning skills were lacking as I can still see the light out of the bottom right corner of the patch. Thanks. ??How long do those dash lights usually last anyway??
     
  8. mayhem

    mayhem PlowSite.com Addict
    from Peru MA
    Messages: 1,016

    Unfortunately the bulb will probably outlast the truck. You're stuck either fixing it or using a screwdriver and a hammer to take out the bulb.
     
  9. CityGuy

    CityGuy PlowSite Fanatic
    Messages: 16,985

    I believe that on that generation truck the brake light comes on when a vehical speed sensor goes bad. If memeory serves right the front pass side sensors go bad before the drivers side. Just a thought to check. They aren't all that expensive to fix.