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How to connect this wiring?

senna1234
Explorer
Explorer
Hey guys.
I have an open trailer that I have a brown wire that is not connected. I am not sure where it goes. I think it will connect to the brown wire attached to the new plug that was put on. If it does, how do I connect it?





thank you!!
19 REPLIES 19

BB_TX
Nomad
Nomad
Here is an easy to follow 4 pin trailer wiring diagram. A new harness and this diagram would make for a much better final product.

westend
Explorer
Explorer
You are probably going to blow a fuse in the truck doing it as you are proceeding. Have extra fuses on hand or for less than the cost of fuses, buy a test light. They are $2.
Turn your lights on in the truck and probe with the test light to see which wire now has power. Connect that to the brown wires leading underneath the trailer. You should have tail and clearance lights. If not, you have a cross-wired trailer wiring schedule and should buy a harness and start over.
'03 F-250 4x4 CC
'71 Starcraft Wanderstar -- The Cowboy/Hilton

senna1234
Explorer
Explorer
Thanks. Last night I connect the loose cable on the side(yellow light) to the light and tried it to the frame. Did nothing. Started to rain so I had to stop. Tonight I plan to connect the loose brown cable by the hitch, double it up with the other brown cable and connect both the the brown cable. (sounds confusing right? ๐Ÿ™‚ )
Hoping that will solve some issues. Not sure I'm ready to rewire the entire thing. Mainly because I'm not sure what I am doing.
I'll report back.
Thanks for the patience with me.

corvettekent
Explorer
Explorer
Those amber lights and the tail lights (headlights on) should be powered by the brown wire.
2022 Silverado 3500 High Country CC/LB, SRW, L5P. B&W Companion Hitch with pucks. Hadley air horns.

2004 32' Carriage 5th wheel. 860 watts of solar MPPT, two SOK 206 ah LiFePO4 batteries. Samlex 2,000 watt Pure Sine Wave Inverter.

westend
Explorer
Explorer
A test light or meter helps this process quite a bit.
As was mentioned, good suggestion to buy a new harness for $15 and wire it all correctly to the proper schedule.

Etrailer harness
'03 F-250 4x4 CC
'71 Starcraft Wanderstar -- The Cowboy/Hilton

BB_TX
Nomad
Nomad
Crawling around under a trailer is not a lot of fun, especially for old guys like me who don't bend and stoop like I use to.

If it is only the tail lights that are not working, I would start at the tail light assembly(s). Locate the wire for the tail light on each side and trace them back until you reach the front of the trailer. Then you can determine where, or if, they are connected. Then you will know which wires to be troubleshooting.

senna1234
Explorer
Explorer
Thanks guys. I'm getting a little confused. Sounds like I might need to start at the yellow side light. Should it be a ground or should it attach to the yellow side light? Once I do that I will see what works. But if nothing changes then I am confused at what to do with the brown wire.
I will work on it this evening and trace a few things out.

Thanks

enblethen
Nomad
Nomad
Locate the brown wire that is spliced to the white. White should be ground. The brown wire connected to it maybe going to the taillight fixture as power lead.

Bud
USAF Retired
Pace Arrow


2003 Chev Ice Road Tracker

BB_TX
Nomad
Nomad
That yellow side light probably only has one wire for power and uses the frame for ground. The wire hanging loose is probably not used, at least for that light.

Even if the "repair place" were next door, I would not take it back to them. That looks like one heck of a mess. It would bug me so much I would just go buy a new trailer harness assembly, rip out that mess that is there, and rewire the whole trailer. In the future when you have problems with one of the lights (and at some point in time you will if you keep it long enough) and have to troubleshoot it, you will appreciate having it wired properly and the color code correct.

senna1234
Explorer
Explorer
Thanks guys. OK, I took some closer pictures. Drivers side yellow light has a cable that is not connected. I will hopefully have time to connect this tonight.

When the truck is connected to the trailer; both turn signals work and both sides work when the brake is applied. When my headlights are on, NEITHER rear light works. I should be able to figure out where the one cable will connect to the yellow side light. I'm thinking I should hook up the side light and see where that gets me. Do you think the not connected brown cable isn't needed because there is already a brown cable connected from the truck to the hitch?

I can email you a picture of the hitch part if you need to see a closer image.
Thanks!!





nineoaks2004
Explorer
Explorer
I use solder less crimp (butt) connectors, (usually blue) auto parts stores, wally world etc. sells them plus I use shrink tubing over the splice and it stays sealed from water etc.
By the time you learn the rules of life
You're to old to play the game

BB_TX
Nomad
Nomad
Do your tail lights (and other lights) work when hooked up?

From the picture it appears you have two green wires coming from the trailer, one connected to the connector green wire and one connected to the connector brown wire. If that is the case I would guess the "repair place" added new (green) wires and used one to connect the tail lights to the brown connector wire. Bad brown wire somewhere under the trailer maybe? If that is the case, the loose brown wire is not needed. Look under the trailer and trace that loose brown wire. Likely you will find the other end not connected either.

Oldenuftoknowbe
Explorer
Explorer
Yep, the brown wires control each of your rear running lights (thus 2 wires). My open trailer is wired the same way.
2016 Starcraft Launch UltraLite 26BHS w/Pro-Series WDH
2013 Ford F-150 Supercrew 5.0L W/factory tow package

enblethen
Nomad
Nomad
You would splice the brown to the brown with a Blue butt connector using properly sized crimper.
Do not use the ones in the previous post. Blue butt connectors
I fill the butt connector prior to crimping with electrical grease.

Bud
USAF Retired
Pace Arrow


2003 Chev Ice Road Tracker