Trailer wiring problem

Install my new hitch & trailer light T connector. I tested the lights with the trailer & they are doing some strange things. The lights turn on, but turn off when I hit the brake, & the turn signals flash both trailer lights.
The trailer lights work fine on another tow truck. It's the standard flat connector.
Has anyone had this happen?

I suspect it might be my rear wig wag flasher screwing it up, but I'm not sure yet. Have to test things. I don't see how however since it's only inline with the rear lights, & the rear lights work normal with the flasher as is.

 

[MountaineerGreen]

Check your ground wire on the truck. Often times a bad ground makes for really strange things.

 

[Jason94sport]

Ground wire? What ground wire? The ground wires to the battery are fine. I have no electrical problems.

 

[MountaineerGreen]

The ground connection to the trailer lights is the green wire on the 4 flat connector. Follow that wire back and make sure it has a good connection.

 

[Jason94sport]

gotcha

 

[Jason94sport]

MountaineerGreen

Thanks! I just got around to figuring this out today. The harness on the trailer didn't have the ground wire connected. Connected it to a bolt on the trailer & the lights work fine.

 

[quick2scramble]

How did you wire this up exactly? The Explorer has 2 seperate wires for turn and stop lights yet the harness only offers one wire for the connection. I'm in the process of trying to wire up the 4 wire harness myself.