Still having trailer light issues

Discussion in 'OnBoard Electronics & Controls' started by Mark B, Oct 16, 2017.

  1. Mark B
    Joined: Sep 2017
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    Location: Ny

    Mark B Junior Member

    When I turn on my running lights the lights all light up like suppose to BUT if you turn on the left blinker both taillights blink but the left side is much stronger and the right side is very dim. If you turn the right turn signal on they both blink again and the right one is much brighter this time. IF you put on the brakes all the lights completely turn off. The vehicle also tows another boat and the light are fine on that trailer so I so no think its a truck issue. Its in the trailer and can someone please help I wanna try to launch soon before I have to put it away for the season. It will be my first time out in it. Any help would be great. Ty guys and gals
     
  2. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    Could be a ground issue. Trailer lights typically use the trailer frame for one side of the circuit.

    Is the ground wire (usually white) on the trailer harness connected to the trailer frame? If not the ground connection to the tow vehicle will be through the hitch. Sometimes the trailer lights will work okay with the ground connection through the hitch but frequently the lights behave as you describe. The fix is a good connection of the ground wire to the trailer frame. If that doesn't solve the problem make sure the ground wire on the tow vehicle harness is connected to the tow vehicle body/frame.

    Because the lights on both sides behave the same the problem is most likely with the harness ground connection. It is also possible that there is a bad or no ground connection at both trailer lamps. If the trailer lamps have ground wires make sure they have a good connection to the trailer frame. If they are mounted on wood or similar make sure the ground wire runs to the metal frame, not just to the wood.

    You can also run a ground wire from the trailer harness to each trailer lamp.
     
  3. Mark B
    Joined: Sep 2017
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    Location: Ny

    Mark B Junior Member

    Also I'm using a 5 wire 4 flat harness
     
  4. gonzo
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    gonzo Senior Member

  5. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    How many contacts are in the connector? Is it 4 contacts and 5 wires? If so two wires go to one contact, presumably to provide a wire for the brake lights on each side.
     
  6. markstrimaran
    Joined: Dec 2014
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    Location: usa

    markstrimaran Senior Member

    What year make model? My AMC JEEP HAS a similar issues. It is in a converter from single tail, brake, to separate brake and turn.
     
  7. Mark B
    Joined: Sep 2017
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    Location: Ny

    Mark B Junior Member

    Yes there are 5wires 4 prong harness. Its a wishbone harness
     
  8. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    What is the white wire on the trailer harness connected to? Your symptoms sound like a bad or missing ground.
     
  9. Mark B
    Joined: Sep 2017
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    Location: Ny

    Mark B Junior Member

    To trailer frame
     
  10. Mark B
    Joined: Sep 2017
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    Location: Ny

    Mark B Junior Member

    2008 ford explorer
     
  11. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    Disconnect the white wire from the trailer frame, make sure the connection surfaces are clean, and reinstall.

    Do the trailer lights have metal frames/shells, or do they have plastic frames/shells? If plastic what are the ground wires from the lights connected to?
     
  12. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    The 5 wire flat connector has one wire for backup lights. The others are the same as a 4 wire.
     
  13. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    Gonzo, its has four connections, the same as "four wire" connectors. The brake light has two wires, one wire for the brake light on one side and the other wire for the brake light on the other side. That means a wire between the brake lights is not needed.
     
  14. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    You should look at the photo in his other thread. There are 4 male and 1 female connections. The males go to parking, brake/left turn, brake/right turn, backup light. The female is white and goes to ground.
     

  15. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    I haven't seen his other thread. It still sounds like a ground problem to me.
     
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