Trailer Wiring Help

[Chesapeake TJAM]

OK I'm getting a little confused and frustrated with my trailer lights. Ran new wire as the old wires had some issues. Hook up to my truck and I don't have running lights. Turn signals L&R work and brakes work, just not the running lights. I believe the "Brown" wire on the truck side is bad. So I hook up to my father in laws truck and I have running lights (thought my problem was solved) but on his truck I don't have turn signals or brakes? WTF. Is the issue with the lights or is something wrong with both of our trucks wiring???
Any suggestions?

[bottom scratcher]

Have you checked the fuses on the truck. Most trucks have separate fuses for the trailer brake and turn lights.

[Chesapeake TJAM]

Nope I haven't but I will and let ya know if that's it. Thanks

[Kirk Grassett]

Check your ground wire. A poor ground can cause all kinds of wierd trailer light issues.

[hippie]

I had that same problem years ago. It turned out to be (I don't remember what it's called) but it is a round thing about 1" in diameter and goes in the fuse box. Take it out and replace it with one that has a higher amp or watt rating and problem solved. Good luck, Bob

[RickyF]

Do you have the flat 4 prong plug or the round plug? If you have the flat plug, you can buy a little tester that you plug into the receptacle on your truck to identify if your harness is wired correctly. It's less than 10 bucks. My guess is that your truck may be wired different than normal.

[BUDC]

Check your ground wire. A poor ground can cause all kinds of wierd trailer light issues.

YES + YES + YES
I have had so much trouble over the years with this that I have now run a separate ground wire loop and grounded every light fixture. It's cheap and takes a few seconds more --- very much worth the effort.
A side note, my '06 GMC p/u with the Tow Package has seperate fuses for ALL trailer lights. One for right side, one for left side, one for running lights. The box is under the hood, separate from the one in the dash which is for the truck lights -- NOT the trailer.
From experience, this will ruin an otherwise beautiful day!!
budc

[Son Worshiper]

You replaced all the wiring on the trailer itself... What about the plug? Check the plug.

Use jumpers to connect each wire... Test each one idividually.

I'm not an expert but it solved some of the problems/confusion that I was having a while back...

[Grady23]

First things first --- Disconnect the trailer from the hitch. This eliminate the ball as a ground point. Start with testing the connections in the socket on the truck. BE SURE that you have a good ground BEFORE you start. You can do this with an OHM meter. Just be sure to set the meter back on 20 or more Volt DC before you start testing any powered connections. Once you've determined that all the wiring is good on the tow vehicle, THEN start testing connections on the trailer starting with the ground. I know you tried the rig on another truck, but that truck could be wired diff from yours. That's why I said start with verifying the wiring on YOUR truck!
Good Luck --- I hate FRIGGIN wiring problems!

[BUDC]

Amen Bro Grady, AMEN!!

[Chesapeake TJAM]

Thanks for all your help fellas. I replaced 1 of the fuses and bingo. Of course now the Left bulb is bad. I have good power on the meter all the way to the bulb so a quick change and I'm good to go. There's always something........