Tail lights

Discussion in 'Audio + Electronics' started by GMC GIANNI, Aug 15, 2019.

  1. GMC GIANNI

    GMC GIANNI OBS Enthusiast

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    All lights on my truck work except the tail lights. Brakes blinkers work I just dont have rear running lights. Any thoughts? Ive re routed the ground wire u der the bed to a new clean spot. Cop said they flickered when i wiggled my wiring assembly at the switch. No proof of that though.
     
  2. fancyTBI

    fancyTBI half-ton fun

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    I am having the same problem. I checked my grounds, re did 1 of them, and still nada. Brake lights work only when lights are on. Check the ground at the rear of the truck. Mine was on drivers side, close to the spring shackle.
     
  3. TechNova

    TechNova I'm Awesome

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    Are your dash lights working? On mine the dash and tail lights would not work or would come on after a few bumps in the road.
    removed the switch, cleaned the terminals and the connector, no more problems.
     
  4. fancyTBI

    fancyTBI half-ton fun

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    Check the harness, too. I have checked mine for the third time and had some cleaner this time so I cleaned it really well, and blew it out with a fine air gun, now it’s working fine. I have brakes, reverse, tail, blinkers.
     
  5. PlayingWithTBI

    PlayingWithTBI Desert Old Guy

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    If you wiggled the harness @ the switch and it flickered then, I would start there like @TechNova suggested.
     
  6. kennythewelder

    kennythewelder B31-3 (6-G) certified

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    Hows you guys circuit boards. I had to replace mine not long ago. The plug ins for the bulbs were falling apart.
     
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  7. DerekTheGreat

    DerekTheGreat I'm Awesome

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    What Kenny said.

    Every GMT400 I've ever laid hands on had an issue with the circuit boards. The reverse lights seem to be the first to go and then it's the brake lights due to rust. In the extreme case, the boards rust so bad that it creeps into the wiring harness... If your sig is accurate, you've got an '89 which still sports the early style board. Those were more prone to rotting out than the later style. Figure out what you've got goin' on back there. If your boards are rotted, try a junkyard or a parts store. You can find new ones from the China express or you can scour junkyards for good ones. I prefer the latter route. Requires more time and requires a multimeter and a good eye though. If corrosion has set into your harness but isn't terrible, you can try cleaning/scrapping it off with a paper clip like I have. When you button everything up, be sure to fill everything with dielectric grease.
     
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  8. GMC GIANNI

    GMC GIANNI OBS Enthusiast

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    The dash lights work when head lights are off. the board you are all referring to is this where the bulbs plug into? those plastic pieces are pretty wrotted. both harness are good, re routed the ground which is good now. I have brand new 3057 bulbs in and nothing. when i click over the headlight switch i can hear almost a little pop. i have cleaned those kinections as well
     
  9. kennythewelder

    kennythewelder B31-3 (6-G) certified

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    Yes. Its the board that the light bulbs plug into. Not only did I have to replace the boards, but I also had to replace the red lens tail lights. Man the new tail lights look grate, and are much brighter. My OE tail lights looked good. I keep them polished, but its hard to beat new parts.
     
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  10. kennythewelder

    kennythewelder B31-3 (6-G) certified

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    The problem with the OE boards is that when they get this old, the little copper prongs inside of them, that connect to the metal prong on the light bulbs, get to where they just dont make a good connection any more. The copper prongs on the boards just ware out over time. I tried to fix mine, but they just fell apart. I used dorman replacements, and so far so good, but you can tell they are not as well built as the OE ones are. Amazon and e-bay both carry them, although I got mine @ Orllies. They were a good bit more, but they had them in stock, and I didnt have to wait for them.
     

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