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Thread: More on trailer lights

  1. #1

    More on trailer lights

    Since we have a couple of threads on this topic, I figured I would throw in one more.

    I have a utility trailer with a 4pin flat light cable, A boat with a 4 pin round connector and an old horse trailer with a vehicle side connector 7 pin round connector and an UGLY hack job to get the connector to 4 wire flat cable. My tow vehicle has a 4 wire flat connector that I hate, hate hate. Always hanging there, hitting the ground, never stays in its holder, get replaced at least once a year. What I would like to do is move all the trailers and truck to one of the round connectors, but what one?
    What are the various round connectors used for, I see 4,5,6,7 and 9 wire trailer connectors. What are each used for?


  2. #2
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    Re: More on trailer lights

    4, 5, 6, and 7 I've seen; never seen a 9 pin. If you'll go to google.com and enter "trailer light plugs" and "trailer light connectors" you'll find more than you want to read on the topic. The 7 pin connectors that I'm familiar with are: (1) ground, (2) taillights, (3) left flasher or turn signal, (4) right flasher or turn signal - the flashers are also the brake lights usually, (5) electric brakes, (6) 12v continuous - to charge a battery or operate a 12v refrigerator or lights in the trailer, and (7) auxilliary - sometimes backup lights on the trailer.

    If it were me, I'd want the 7 pin connector on the truck, and then there are plenty of adapters on the market to go down to whatever circuits are needed for each trailer, or of course, you could put 7 pin connectors on all your trailers but only have the circuits needed wired into the trailer plugs.

  3. #3
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    Re: More on trailer lights

    There must be something fairly standard about the 7 pin round connector. My truck came with one from the factory which included a jumper harness under the dash for a brake controller. Our fifth wheel camper works fine with it as does my flatbed trailer. I've got an adapter to convert it to a four pin flat, but have never needed it [img]/forums/images/icons/smile.gif[/img]
    Rob

  4. #4
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    Re: More on trailer lights

    Bird has it right, in my opinion. Convert the truck to 7 pin with all the necessary wiring and use the adapters locally available to convert it to 4 wire flat. Convert the other trailers to 4 pin as well.

  5. #5
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    Re: More on trailer lights

    There are actually standards for most trailer/RV wiring, and a search of the web will get you some diagrams. Seems a lot of folks over theyears hooked things up any way they saw fit, so sometimes even a simple 4-wire round connector might fit your buddies car but no your truck.

    Not sure when they set some standards, but it is nice that they did!

  6. #6
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    Re: More on trailer lights

    Bird,
    You are sooooo right! I wired my old truck up 7-wire rv round. Took the time to do brakes, since I towed the tractor on a trailer. Had backup lights for the horse trailer. The newer Dodge was pre-wired 7-wire from the factory.

    I set the horse trailer up 7-wire. Set my old slide-in camper 7-wire. My new truck, and flatbed trailer are 7-wire. Every possible accessory works.

    I have a 7-wire to 4-flat adapter. I also have some pigtailes so I can adapt to 4-wire round, and 6-wire round. I can pretty much adapt to anything; pretty easily too.

    I have found it is easier to adapt down than up. It's hard to adapt up from a 4-wire flat to a 6-wire round.

    I am pretty well set on my own "towables", so adapting usually isnt necessary. And, on all my "towables", all the options are on them for lights, brakes, and charging.

  7. #7
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    Re: More on trailer lights

    Truck wiring:

    Mine has a seven pin for the trailer, a flat four for the shell, and another seven pin for the camper.

    Canadian and US 7 pins are wired differently.

    Egon


  8. #8

    Re: More on trailer lights

    Ok, you have convinced me, Its 7 pin round. Now which 7 pin round? There appears to be a 7 POLE round FLAT PIN (RV STYLE) and a 7 POLE round, ROUND PIN style.
    http://www.championtrailers.com/TRAILER_RECEPTACLES.htm shows both types.

    Now once we figure out what 7pin round, I am assuming the RV style is the one, how do I mount it. I found in my searching a 7pin rv style vehicle connector with a bracket that also had a 4pin flat in the same bracket. This would be nice and keep me from needing an adapater is I am pulling a friends trailer.

    Does anyone know who makes the bracket with both a cutout for round and flat 4. I cant find it now that I need it.

  9. #9
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    Re: More on trailer lights

    <font color="blue"> "a 7pin rv style vehicle connector with a bracket that also had a 4pin flat in the same bracket. This would be nice and keep me from needing an adapater is I am pulling a friends trailer" </font color>

    What are you going to do when you want to borrow my trailer with its six round plug? [img]/forums/images/icons/tongue.gif[/img] To cover that you'll still need an adapter. [img]/forums/images/icons/wink.gif[/img] [img]/forums/images/icons/smile.gif[/img] [img]/forums/images/icons/grin.gif[/img] I still think the seven with the 7 to 6 adapter and 6 to 4 adapter is the way to go. [img]/forums/images/icons/crazy.gif[/img]

    As to the bracket, my set up (six round and flat four together) came with one. I mounted mine directly into my bumper so I didn't need it but it was part of the package. I'd think you could find one like that, too. Mine was a 'Hoppy' brand from TSC.

    Good luck with whatever you decide. I hope this helps. [img]/forums/images/icons/smile.gif[/img]

  10. #10

    Re: More on trailer lights

    Gary, Your a little far to travel to borrow a trailer and would buy an adapter if I ever needed it. Every tailer at the two rental yards I use are 4 wire flat, Every trailer I have borrowed in the past has been 4 wire flat. Every boat trailer I have pulled for a friend has been a 4wire flat. Ill need a 4 wire flat one way or another, If it can in the same bracket so much the better.

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