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Fixing my trailer harness, need help

Discussion in 'Chevy Trucks' started by obrut, Oct 13, 2009.

  1. obrut

    obrut Senior Member
    from IL
    Messages: 147

    I have a 2000 GMC NBS, I bought the truck with the hitch and wiring already on there. When I went to pull a trailer the lights were not working right. I looked under the truck and it looks like they tied into the yellow, green and brown wires and thats it. I removed the old 7way trailer harness connector. It looks like there is a factory plug under there with a cap on it and then a single light blue with with a connector on it. I think this is where the 7way would get connected but what is the light blue wire for? Also I think I'm going to cut off the factory connector and then wire up my new 7way connector to those wires. Does anyone have a wiring diagram for that connector?

    Tim
     
  2. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    The connector you're seeing is for the factory trailer plug. And the other capped single light blue wire is for a center mounted brake lamp. It's on the same circuit as the one on the rear of the cab.
     
  3. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,992

    Don't cut it, go to a trailer parts dealer and buy a plug in connector. Be well worth it the first time you have a plug problem. lot less issues and corrosion. If you want 12 volt charge line and electric brake control plug in the convenance box to work you may need to hook some wires up under the hood.
     
  4. obrut

    obrut Senior Member
    from IL
    Messages: 147

    I would leave it but its all corroded, so I need to cut the wires from the factory connector and then use ring terminals to connect to my new 7way. I think the yellow is the left turn the green is right turn, and the brown is tail lights, what are the other ones?
     
  5. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Green - R Turn
    Yellow - L Turn
    Brown - Marker
    White - Ground
    Lt green - B/U lamps
    Dk Blue - Trailer brakes
    Red - Trailer charge

    If you're planning to cut into it be sure to use sealed connectors or plenty of heat shrink tubing. Seal them up well...
     
  6. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,992

    It's correded under the cap? sounds like it was never used if the cap is still on it.

    B&B gave you the truck wire colors, here is the plug configuration if you are going to cut and strip????

    Black; AUX 12 volt
    Blue; brakes
    White; ground
    Brown; right turn
    Red; left turn
    Green; tail markers/parking lights
    Center; reverse
     
  7. obrut

    obrut Senior Member
    from IL
    Messages: 147

    thanks for the help guys, I'm going to finish wiring it up tonight. The new 7way connector I bought did not come with any wire. I'm going to crimp terminals on the wires and then screw them to the terminals on the new 7way.

    Thanks,
    Tim