At each light there is a connector for power and a ground wire going to the trailer via tapped screw. And the main hardness going down the trailer frame on inside held on by zip ties or wire ties with screw. Good luck on your search! Remember to pull hard on every connection to check if the wire is rotted inside the jacket.
A complete new wiring harness is the best way to tackle it, if one wire has rotted and shorted you will be chasing the issue on others for the next few years and its not worth a ticket on your way home from fishing. It can be a parking lot job, as its just laying out the wires and connecting each light via the connectors or butt connector and shrink wrap. Its much easier to do with the boat off the trailer
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