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No brake lights... help?

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by 72BlazerTravis, Dec 26, 2002.

  1. 72BlazerTravis

    72BlazerTravis Registered Member

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    Went in for an inspection today and aside from having a few spots where my dual exhaust leaks,my brake lights aren't working. I looked underneath and there is a place where some dumbass didn't know what he was doing and tried to install trailer wiring. So after all that crap was removed I was stuck with the 4 (or is it 5?) wires that come directly out of the harness in the rear.

    I touch every wire on every other wire and I still get no brake lights? Does anyone know which wire (color) is for the brakes? Doesn't your 4 way flashers flash your brake lights and not the turn signal lights? I turned on the flashers and they don't work in the back, I have no idea what wire goes to what?

    I'm getting po'd.

    Thanks in advance. /forums/images/graemlins/confused.gif
     
  2. bouncytruck

    bouncytruck 1/2 ton status

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    Here's a link to the wire diagrams that a very kind board member scanned and posted on the web. (I don't remember who it was, but thanks!)
    http://www.geocities.com/chevroletc1070/wiringdias.html

    You can also get a new rear harness from most of the dealers. Chevy Duty has the front tail lamp harness - from the firewall to the rear - listed at 38.95. The rear tail lamp harness - connects to the front tail lamp harness to the lights - is listed at 78.95 for a blazer. Make sure you check the ground straps too.
     
  3. Topdown

    Topdown 1/2 ton status

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    Just as a point of interest... my brake lights come and go also and I found that it was because they have/had a bad ground. The tail lamps ground themselves to the body via the screws that attach them to the truck. So, if I ground the housing to the body they work... when that ground goes bad, I have to clean it off and they work again. I believe either the same dumb-ass that you described or one of his/her relatives wired in my triler hitch as I had to gut all the spaghetti wiring under the butt of the Blazer to get my taillights to work also. Not to mention the trailer hitch being welded to the frame, then some strange little steel pieces, about an inch across and 6 inches long welded from the trailer hitch to of all places, the bottom of the bed... wtf is that all about.

    Anyway. Hope that helps.
    -Ryan /forums/images/graemlins/k5.gif
     
  4. 72BlazerTravis

    72BlazerTravis Registered Member

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    Thanks that will help. /forums/images/graemlins/smile.gif I'm wondering why my blinkers work but my flashers don't. Maybe it's that little sensor up at the brake pedal that isn't ground good and that is why my brake lights don't work. Oh well, I'll figure it out this weekend when its warmer. Only been in the 30's here all week and snow so I haven't been able to mess with it too much.
     
  5. bouncytruck

    bouncytruck 1/2 ton status

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    Make sure that the body is properly ground. even if your tail lights are ground to the body, if the body isn't ground, or the ground strap is going bad, you may have intermittent breaks in the circut. I tested mine a while back nothing beyond the block was properly ground.
     
  6. 72BlazerTravis

    72BlazerTravis Registered Member

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    Finally figured out what the probalem was. That little sensor deal that senses when the brake is pressed was rusted in place! It wasn't popping up to trigger the brake lights. Little WD-40 and that fixed that. Also I think the main problem is my damn turn signal lever. I lubed it up too but I notice if it's in a certain spot the lights act quirky. Damn old cars! /forums/images/graemlins/thumb.gif
     
  7. bouncytruck

    bouncytruck 1/2 ton status

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    Both the brake light switch and the turn signal switch are available new in most of the catalogs. The turn signal parts tend to break and not work very well. Mine is really sloppy and it doesn't shut off after I turn a corner.
     
  8. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    </font><blockquote><font class="small">In reply to:</font><hr />
    The turn signal parts tend to break and not work very well

    [/ QUOTE ]

    ....I hear ya on that one! I finally got an unbroken turn signal stalk in mine with some good cancelling springs. For the first time in 2 years, my directionals "self cancel" like they're supposed to.....

    Unfortunately, they sometimes cancel before I've even made the turn (too sensitive to slight wheel movements).....but HEY, it's a start! /forums/images/graemlins/grin.gif
     
  9. POFF

    POFF 1/2 ton status

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    Turn signal switch is available from the dealer GM# 1972751 (non-tilt, I don't know if tilt is the same) . The new switches come with the later style straight plug. If you current switch has a curved plug you will need an adapter, I don't know who has them, I got mine from the junkyard. Grounds and dirty sockets are always problems in old vehicles.
     

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