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  1. #1
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    Trailer Wiring Problem

    Marker lights and tail light does not work on right side of trailer. Don't know if back up light works on that side. All other lights work. Brown wire bad? or Ground wire issue? Grounded at each light to trailer with a connection riveted to trailer. These seem tight. Trailer is tube frame with swing away tongue. Have pulled the wiring out of the swing away tongue and examined from the 5 flat connector to where the tongue hinges and where it comes out of the frame to each light and wiring that is accessible to visual inspection seems to be in good condition. I have tested the bulbs in all 3 lights and they show continuity. Could someone point me in the right direction? Thanks!

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    #2
    Check the power at the flat plug first at the truck then to trailer. Use a tester and after tk to tr if it's good check for good ground which should be good just by hooking up the plugs (not with the trailer hooked to vehicle because it then can ground through the ball). If the lights don't work without hooking the trailer to the truck there is probably a bad ground assuming the truck has a good ground. Most wiring problems are ground but in a tube trailer it can also be a broken wire in the tube. It is all time consuming and aggravating.
    Rocket

  3. Member Bass AHolic's Avatar
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    #3
    to fast test back up trailer lights, engine off, park brake on. put in reverse gear, have to leave ignition on probably, and walk back to look

  4. Electrical/Wiring/Trolling Motors Moderator CatFan's Avatar
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    #4
    Somewhere between the plug and the back of the tongue, the brown wire will split into two wires. May both be brown, or one may have a yellow stripe and the other green. Likely your problem is where it splits.
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    #5
    Quote Originally Posted by CatFan View Post
    Somewhere between the plug and the back of the tongue, the brown wire will split into two wires. May both be brown, or one may have a yellow stripe and the other green. Likely your problem is where it splits.
    ^^^^wot he says. Brown is running lights, and half yours work so that eliminates the disconnect interfaces.

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    #6
    Quote Originally Posted by Cliffprocraft190 View Post
    Marker lights and tail light does not work on right side of trailer. Don't know if back up light works on that side. All other lights work. Brown wire bad? or Ground wire issue? Grounded at each light to trailer with a connection riveted to trailer. These seem tight. Trailer is tube frame with swing away tongue. Have pulled the wiring out of the swing away tongue and examined from the 5 flat connector to where the tongue hinges and where it comes out of the frame to each light and wiring that is accessible to visual inspection seems to be in good condition. I have tested the bulbs in all 3 lights and they show continuity. Could someone point me in the right direction? Thanks!
    Both back up light do not work. I'm thinking brown wire is broke somewhere inside tube frame.

  7. Electrical/Wiring/Trolling Motors Moderator CatFan's Avatar
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    #7
    Quote Originally Posted by Cliffprocraft190 View Post
    Both back up light do not work. I'm thinking brown wire is broke somewhere inside tube frame.
    Backup lights have no connection with the running lights. Different circuits completely.
    If you have integrity, nothing else matters. If you don't have integrity,
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  8. Member fishnfireman's Avatar
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    #8
    If I'm reading this correctly - you have no clearance/tail lights on the right--- no reverse lights on either side... however your turn/brake lights work on both sides and each light has it's own ground ??
    If they are individually grounded --with that many not working I doubt it's a ground issue...
    First I would make sure with a simple 12 volt tester that you are getting power to the trailer on the pickup side.. Then check to see if your getting power to the affected lights.

    If you have power at the plug but no power at the lights then odds are you have a break or a bad connection somewhere in-between.
    My guess is the reverse lights both feed from the right side. Most often the problem will be at a connection...As someone stated above try to find where they split.

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    #9
    Quote Originally Posted by fishnfireman View Post
    If I'm reading this correctly - you have no clearance/tail lights on the right--- no reverse lights on either side... however your turn/brake lights work on both sides and each light has it's own ground ??
    If they are individually grounded --with that many not working I doubt it's a ground issue...
    First I would make sure with a simple 12 volt tester that you are getting power to the trailer on the pickup side.. Then check to see if your getting power to the affected lights.

    If you have power at the plug but no power at the lights then odds are you have a break or a bad connection somewhere in-between.
    My guess is the reverse lights both feed from the right side. Most often the problem will be at a connection...As someone stated above try to find where they split.
    Yes, you understood me correctly as to which lights are working. I have tested the truck (Dodge with 7 way round) and I have plugged in my 7 round to 5 flat adapter and tested it and they are fine. It is on the trailer. There are plastic caps in the ends of the tubes on the trailer that contain the back up lights and I can remove the caps to check the wires going to the back up lights and I could use a wire snake to pull a new wire down the right side of the trailer. That would be easy. The hard part is that the manufacturer put a small hole in the tube near each marker light and tail light location and pulled a small loop of the 3 wires (molded together as a 3 conductor strip) out where they could be separated and the short wires from the lights could be attached with connectors. I'm not sure what they used to grab the wire in the tube and pull it out through the hole, and I have a set of picks and one has a hook in the end, but I think it would be very hard to connect with the wire in the tube and bring it out.

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    #10
    Quote Originally Posted by CatFan View Post
    Backup lights have no connection with the running lights. Different circuits completely.
    Yeah, so I thinking I probably have two bad wires on that side of the trailer. One a hot wire to the tail light and one a hot wire to the backup light. I'm thinking the ground is probably good since I have turn signal and brake light.
    Am I thinking about that correctly?

    There is also a blue wire down each side for backup lights, so I'm thinking the brown and the blue wires are bad; the blue in the swing away tongue before a second blue is spliced on to go to the other side, the brown somewhere in the right side of the tube frame.
    Last edited by Cliffprocraft190; 03-12-2017 at 11:50 PM.

  11. Electrical/Wiring/Trolling Motors Moderator CatFan's Avatar
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    #11
    Quote Originally Posted by Cliffprocraft190 View Post
    Yeah, so I thinking I probably have two bad wires on that side of the trailer. One a hot wire to the tail light and one a hot wire to the backup light. I'm thinking the ground is probably good since I have turn signal and brake light.
    Am I thinking about that correctly?

    There is also a blue wire down each side for backup lights, so I'm thinking the brown and the blue wires are bad; the blue in the swing away tongue before a second blue is spliced on to go to the other side, the brown somewhere in the right side of the tube frame.
    The blue wire goes first to the solenoid to lock-out the brakes when you are in reverse, then to the backup lights. The fact that both are out would make me guess that your tow vehicle has a blown fuse or missing relay/fuse. Most have a dedicated fuse and relay for trailer backup wiring, and often this isn't installed from the factory. On Dodges, I believe this is in the box under the hood.

    The odds are still very high that your running light problem is where the two brown wires split. Breaking a wire inside the tube would be pretty long odds, and if it broke you'd have a bare wire inside a metal tube so you'd probably end up with a fuse blowing occasionally.
    Last edited by CatFan; 03-13-2017 at 09:08 AM.
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  12. Member fishnfireman's Avatar
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    #12
    Quote Originally Posted by Cliffprocraft190 View Post
    Yes, you understood me correctly as to which lights are working. I have tested the truck (Dodge with 7 way round) and I have plugged in my 7 round to 5 flat adapter and tested it and they are fine. It is on the trailer. There are plastic caps in the ends of the tubes on the trailer that contain the back up lights and I can remove the caps to check the wires going to the back up lights and I could use a wire snake to pull a new wire down the right side of the trailer. That would be easy. The hard part is that the manufacturer put a small hole in the tube near each marker light and tail light location and pulled a small loop of the 3 wires (molded together as a 3 conductor strip) out where they could be separated and the short wires from the lights could be attached with connectors. I'm not sure what they used to grab the wire in the tube and pull it out through the hole, and I have a set of picks and one has a hook in the end, but I think it would be very hard to connect with the wire in the tube and bring it out.
    That can be a PIA with the tube trailers-- depending on the size of the hole-- it can be done with a pick hook and a good light if you have steady hands and good eyes. If you run new wires be sure to leave enough so that when you do get them hooked you can pull it out the hole and make your splice/connections then stuff it back in.

    I believe you said you had power at the plug....... then it is not a blown fuse!

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    #13
    Did not get to further checking over of trailer wiring before I went on a weekend fishing trip. Right marker light in front of fender started working, so maybe it is mainly faulty grounding at rear marker and tail light?

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    #14
    Quote Originally Posted by Cliffprocraft190 View Post
    Did not get to further checking over of trailer wiring before I went on a weekend fishing trip. Right marker light in front of fender started working, so maybe it is mainly faulty grounding at rear marker and tail light?
    Anything's possible, but you just need to get on the ground and start inspecting your wiring and taking some voltage readings. Trailers take a beating and lights don't like being dunked.