How do you attach light wires to boat trailer frame?
There are a couple of safe ways to attach the wires. First is to run the wires through the inside of the frame rails. this protect the wires from abrasion and from being cut, pinched, or severed easily. The next best is to get a bunch of Electricians Zip Tie mounts. These have a sticky foot so that they can be mounted anywhere. Then you install small ZIP ties into the slots and form a loop. Run the wires through the loops to where you need them to go. Once you have the wires placed and connected, snug up the wires and clip off the extra ZIP tie and work toward the front of the trailer doing the same as the last. Once you reach the tongue of the trailer, be sure to leave plenty of wire for the connector plug to the tow vehicle (usually about 4' beyond the coupler). Then your done.
If your asking the ground wire attach to the bolts holding the light bracket on run it back up to the plug the white wire has to be grounded to the trailer and the truck.
If your frame is hollow, use a fish to bring the wires through the frame. Some things you want to watch out for is corrosion of the trailer, and the wires flapping in the wind, or the wires snagging on something when trailering. That being said if you have to mount the wires externally use enough enough clips to keep the wires snug to the trailer. Be sure to seal the holes you drilled for the clips with silicone or rust preventive paint. If you can go through the frame internally, you need only secure the wires with clips at entry and exit points.
The colour code for trailers is as follows, white-ground, brown-running, yellow-left turn, green-right turn and blue would be for trailer brakes if your trailer has them or auxiliary. If your adapter (on the Dakota) is hooked up properly those are the wire colours that run from your vehicle into the trailer lights and the signal lights will also be the brake lights.