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Thread: *$^&#)* Trailer wiring!

  1. #21
    Member mjm316's Avatar
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    When you get yours fixed Mr Pid I'll let ya come and practice a little on my trailer. I'll buy the beer
    Tomorrow isn't promised. "Never delay kissing a pretty girl or opening a bottle of whiskey." E. Hemingway

  2. #22
    Member JOAT's Avatar
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    Having never seen a 7-pin trailer connector with pre-attached wires...

    Just loosen the screw on each terminal and move the wire to the right spot. At this point in time, the colors don't matter and you don't have to mess with whatever wire you spliced together already.

    There are multiple "standards" with trailer wiring. Especially when you transition from 4 to 6 to 7 pin connections, you'll find a variety of different configurations used. Color codes are never a good indicator of what's what on trailer wiring. And neither is the tow vehicle. Different manufacturers use different wire colors and some use slightly different pinouts depending on application.

    On a 7-pin RV connector, go by pin numbers and ignore any wire colors. Pin 1 should always be connected to negative chassis ground. Pin 2 would be brakes if the trailer and truck are so equipped (if neither is equipped, this pin might be hooked to something else, so be careful). Pin 3 should universally be running and tail lights. Pin 4 could be a 12v hot for a charging or aux power circuit (again, not universal). Pin 5 should be your left turn/stop signal. Pin 6 should be your right turn/stop signal. And the center Pin 7 could be anything from an auxilliary power circuit to back-up lights.

    Good luck.
    Winter is Coming...

    Go GeocacheAlaska!

  3. #23

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    Quote Originally Posted by JOAT View Post
    Having never seen a 7-pin trailer connector with pre-attached wires...

    Just loosen the screw on each terminal and move the wire to the right spot. At this point in time, the colors don't matter and you don't have to mess with whatever wire you spliced together already.

    There are multiple "standards" with trailer wiring. Especially when you transition from 4 to 6 to 7 pin connections, you'll find a variety of different configurations used. Color codes are never a good indicator of what's what on trailer wiring. And neither is the tow vehicle. Different manufacturers use different wire colors and some use slightly different pinouts depending on application.

    On a 7-pin RV connector, go by pin numbers and ignore any wire colors. Pin 1 should always be connected to negative chassis ground. Pin 2 would be brakes if the trailer and truck are so equipped (if neither is equipped, this pin might be hooked to something else, so be careful). Pin 3 should universally be running and tail lights. Pin 4 could be a 12v hot for a charging or aux power circuit (again, not universal). Pin 5 should be your left turn/stop signal. Pin 6 should be your right turn/stop signal. And the center Pin 7 could be anything from an auxilliary power circuit to back-up lights.

    Good luck.

    What Joat said is the reason I made a test cable.

  4. #24
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    I don't prefer replacement plugs. I like molded cables. With this crappy weather killing the weekend my solution was simple. Featherlite uses a 7pin molded cord with a weather-proof rectangular plug at the trailer end. I called them and bought a new factory cord. I hate corrosion and this will ensure I won't have any. I'm a pretty handy guy with wiring. I'm still laughing at myself over this episode. :-)

  5. #25
    Member JOAT's Avatar
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    Yep. I've wired a lot of boats and trailers over the years. Corrosion is the killer (especially at the ground connection point), so the fewer breaks you have in a wire, the better off you are. I always make it a point to run a single continuous length of wire from the end device (e.g. light) all the way to the trailer connector. Every connection is soldered and heat shrinked. I try to avoid lights with pigtails and find waterproof housings that use a connection plug on the light housing itself. The connector is then soldered and heat shrinked to the wiring harnes. The plug & receptacle on the connector is loaded up with dielectric silicone grease. Further, the lights with plug connections generally have a ground wire. I avoid lights with mounting hole ground connections at all costs. I'd much rather run a hot and a ground wire from the trailer connector all the way to the light.

    If the trailer came out of our shop, it has a separate pipe conduit welded to the inner frame to protect the wiring forever. Sections of wire running between conduit are taped, covered with corrugated plastic and then taped again. Most commercial trailers have a few hangers here and there. The wiring on those trailers will never last as any exposed wire will be damaged at some point down the road.

    At the trailer connector, I prefer the 7-pin RV with the screw-clamps for each pin inside the plug. I can run all my trailer wires from the lights up to the coupler and secure them properly all the way up. The very last step in wiring is to bring all the wires into a single protected and flexible harness cover from the exit on the side of the tongue up to the proper length needed. Cut them all at the right length and then solder & heat shrink ring connectors on the end of every wire. In my experience, the plugs will get trashed with use. Having all the wires on ring connections means you can drop $8 on a new plug connector as needed and spend about 3 minutes changing the plug out on the trailer by unscrewing from one and screwing right onto the other, with a fresh coating of dielectric silicone grease over everything that is metal.
    Winter is Coming...

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  6. #26
    Member JR2's Avatar
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    I finally give up on a couple of the trailers I have owned and just made a light bar for them. Nice piece of aluminum with lights mounted on the end and a long cord with a plug on the end. Its handy to to move to whatever you are towing at the time and easy to fix if it does have a problem.

    Oh and my Dad's single most important teaching on trailer wiring "Its always the ground"..... and that is usually the problem.
    2007 Kingfisher 2825 - Stor Fisk

    Civilization ends at the waterline. Beyond that, we all enter the food chain, and not always right at the top. -- Hunter S. Thompson

  7. #27
    Member JOAT's Avatar
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    2nd that. 99% of all trailer connection problems are the ground. If nothing works, check the ground at the tongue connection. If the trailer grounds through the ball, run wires. If they come out of the plug and attach to the tongue somewhere near the coupler, then that's the problem. And don't forget to cross check to the vehicle. A lot of the sockets wired on trucks (aftermarket) are grounded the same way and that part will rust out and disconnect.

    If it is one lamp assembly that went out, it probably has a mounting bolt ground connection on the lamp assembly and that's no longer conducting electricity.
    Winter is Coming...

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  8. #28
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    [/QUOTE]

    For the record... I received my new cord from Featherlite, plugged it into the trailer and truck, and it works perfectly. Using the referenced pins in the diagram above here's the Featherlite scheme. Actually the cord is produced by JKD Products, a Featherlite supplier who manufactures trailer wiring harnesses.

    1- Yellow, L turn and brake lights
    2- Blue, back up lights
    3- Green, R turn and brake lights
    4- White, Aux power (interior dome lights in my case)
    5- Red, brakes
    6- Brown, clearance lights
    Center- Black, ground

    The Featherlite scheme matches my 2012 GMC pickup socket. Thanks for all the replies and advice. If nothing else we've reinforced my original statement that there is no standard! :-)

  9. #29
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    So your saying that ;

    1-Yellow, Lturn and brake lights is located where, 1-White ground is on the diagram and

    3- Green, R turn and brake is located where 3- Brown Tail lights is on the diagram, etc.?

  10. #30
    Member JOAT's Avatar
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    I cannot believe how far off of the "old standard" they changed the pinouts on your Featherlight/GMC list. I know there are variations in wire color as well as the use of a couple of the "extra" pins on a 7RV plug, but that is rediculous that they rearranged the "standard" stuff such as turn signals and tail lights. And putting Ground on the center pin has got to be the stupidist idea I've ever seen. The original use of the center pin was for auxilliary battery positive. Thus, if you plug one of these Featherlight plugs into an old truck, you just made a dead short between the truck battery/charging circuit and the trailer's ground. Since the trailer ground is going to loop back through the ball, you might as well just weld your trailer to the truck. What the heck?
    Winter is Coming...

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  11. #31
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    Quote Originally Posted by JOAT View Post
    I cannot believe how far off of the "old standard" they changed the pinouts on your Featherlight/GMC list. I know there are variations in wire color as well as the use of a couple of the "extra" pins on a 7RV plug, but that is rediculous that they rearranged the "standard" stuff such as turn signals and tail lights. And putting Ground on the center pin has got to be the stupidist idea I've ever seen. The original use of the center pin was for auxilliary battery positive. Thus, if you plug one of these Featherlight plugs into an old truck, you just made a dead short between the truck battery/charging circuit and the trailer's ground. Since the trailer ground is going to loop back through the ball, you might as well just weld your trailer to the truck. What the heck?

    Exactly, either that or he did not explain it correctly.

  12. #32
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    My Featherlite has been with me through a few trucks and their plugs have all worked fine. A friend has a different brand trailer and his ground is also the center pin. My stuff is fixed and working fine. Y'all can discuss theory. My issue is solved!

  13. #33
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    Quote Originally Posted by Mr. Pid View Post
    My Featherlite has been with me through a few trucks and their plugs have all worked fine. A friend has a different brand trailer and his ground is also the center pin. My stuff is fixed and working fine. Y'all can discuss theory. My issue is solved!
    Is that a yes, or no to my question in post #29?

  14. #34
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    I indexed Featherlite's colors to pin positions with the index notch at the bottom according to the diagram Featherlite sent me. I'm guessing that's a yes to your question. In any event the fact that my ground is in the center and a friend's trailer and truck match mine? Interesting. Google up 7 pin wiring diagrams and you'll find several variations. Crazy stuff. I'm just happy to have mine fixed.

  15. #35
    Member JOAT's Avatar
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    Somewhere along the way, someone must have redone the "standard" if trucks are coming from the factory with the center pin set as ground and the pinouts as you posted. I have a very, very old "standard" pinout chart in the shop that shows the wiring for the 7 pin RV connector. It's been there for probably 20 years or more. The center pin is "auxiliary/battery/charging" and matches the image that was posted earlier in the thread.

    I've not hooked my truck (which is wired per that image) to a newer factory trailer, but this is going to make sure that I check things out before I ever do. Glad you posted this.
    Winter is Coming...

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  16. #36
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    The white/black reversal of "typical" function has me scratching my head. Maybe the Featherlite drawing is incorrect. Black is ground.... Or is it? I'll grab a friend and map my truck plug with a multi meter when I get a chance. I'm curious.

  17. #37
    Member JOAT's Avatar
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    Black was the standard "ground" color. However, most automotive applications are now running white as the "chassis ground" and adding a black stripe to 12v negative returns on fully looped circuits. So, you once had a red wire run from 12V+ to a lightbulb and a black wire from the bulb over to a chassis ground point. Now you may have a colored wire running from a switch or control out to the light or device and then the same color wire with a black stripe is running back on the negative leg where it will eventually tie into the 12V negative leg off the battery. With all the plastic and such being used, you can't rely on a chassis ground being available, so they usually run two wires out to each gizmo.

    Of course, you can't rely on any color or color/stripe combo to mean anything across platforms. Seems like every auto manufacturer uses a different color code for their vehicle wiring. I just put a new stereo in a newer model Pontiac a couple weeks ago. Absolutely nothing in the car's wiring colors matched the "standards" for car stereos.
    Winter is Coming...

    Go GeocacheAlaska!

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