Ground your lights close to where they mount.
The lights on the side of the trailer are for running lights only.

The plug on your trailer that plugs into your towing vehicle gets grounded at the tongue of the trailer.

white = ground
brown = tailights/running lights
yellow = left brake/trun signal
green = right brake/turn signal

I'd like to do my trailer too but it's all tubbing and not channel so I don't have a clue how to pull the wire for that.  Any suggestions?

Thanks Rod, I think that's one of the few times that the color code was described.

I've haven't seen any of the rectangluar tube type trailer frames that didn't already have holes in it for the wires to run down inside the tubes. I took several steel wire coat hangers and tack welded them together to get the wire down the tube, used a hook/pic tool to grab the wire and pull it through the frame. If holes are not already there then you have two options that I am aware of. Drill or cut holes with a torch (hey - that's how the factory does them plus it gives a smoother/burr free hole) and run the wires dsown the inside of the tube or tach weld washers every 4 feet or so and run the wires inside the flat washers that you just tacked on the trailer frame. Tach the washers at a 90 degree as compared to the frame.

how was it done before? i assume you can run it inside.

The wires are on the inside of the tubing.  I was just thinking about new wire since everything else has been screwed up.  I guess I'll wait until I tear it down to repaint.

I'd like to do my trailer too but it's all tubbing and not channel so I don't have a clue how to pull the wire for that.  Any suggestions?

Thanks Rod, I think that's one of the few times that the color code was described.

25 ft Fish tape. Available @ home depot for 20-30 bucks!

or, if you know an electrician - a fish tape is standard issue!