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trailer light issues

Discussion in 'Chevy Truck Talk & GM News' started by wolfmann, Jul 26, 2012.

  1. RayVoy

    RayVoy Well-Known Member 2 Years 1000 Posts

    I think your right. I don't recall the lighting on the rear of your truck, but if you have a different bulb for sig and brake (on each side), it is probably the flasher unit.

    Some trucks (like I said, don"t recall the Silverado), have separated sig and brake circuits (quite sure the Serria is separate, I remember the sigs being amber). One of the jobs of the flasher is to output these two leads into one for the trailer connector.

    Try a new flasher, that will probably solve the problem.
  2. pmf608

    pmf608 Epic Member 5+ Years 1000 Posts

    I would suggest before you replace the flasher unit that you take a look at the junction box at the rear of the truck. Sometimes they can get corrosion/moisture. Follow the wiring for your trailer plug (and tail lights, etc.) to a box where all of the harnesses for the rear lights meet and a main harness from the front of the truck goes in. Unplug everything, take the junction box off and make sure everything is OK inside of it. If not, then check your flasher. I had to replace the flasher on my Avalanche due to it making the right side trailer signal work, but not the brake light on that side.
  3. wolfmann

    wolfmann Member

    I'm at work now so I can't get to the truck, but are u referring to the junction on The rear crossmember where the blue harness plugs in and splits to the taillights and markers cause the trailer wiring doesn't connect to it. Or is there another junction that you are talking about??
  4. wolfmann

    wolfmann Member

    Thanks to all I did figure out it was th flasher unit causing the problems. I got lucky napa had them for $29 where everyone else wanted $75!
  5. pmf608

    pmf608 Epic Member 5+ Years 1000 Posts

    Thats a good price. My local Napa here in Canada wanted $135 for one, but I got one at Canadian Tire for $80. BUT, that was for the upgrded LM-487 model that is LED compatible. Either way, $29 is good. I'm glad you got your problem fixed.
  6. dpeter

    dpeter Rockstar 4 Years 500 Posts

    Thanks for letting us know what the fix was. I am curious, did the truck lights work OK but just not the trailer?
  7. wolfmann

    wolfmann Member

    The trailer lights did the following right tail light was constant on, the left signal acted like hazard flaahers and right turn signal didn't. Work at all. On the truck every now and then the left turn signal acted like the hazards. But it only did that when cold

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