Tony, The issue is usually the side clearance lights, though the light bar also can be an issue. They are supposed to be checked when they are in production and that set up has individual breakers to throw. Though if a clearance light got twisted is shipping it could pinch the wires and ground it to the light housing. Undo those and check the wires. If that doesnt work, then lets try this! Take a battery lead direct, and run a pair of wires from whatever the source is. Be that boat, go cart, motorcycle, lawn mower (you dont need it yet up there) whatever has a 12 volt source. Go direct to the battery direct with two leads. You can use a vise grip or whatever to hold the ground on the trailer. This is a bit more challenging as you are messing with 12 volts and no breaker. The wires will get HOT if you hold it to ground. Run the leads out, one to a ground on the trailer and the Positive lead just tiche (lightly touch) the prongs on the trailer and see if they arc or the lights work. This will put you to the source of the issue, whether it is the right or left or the tail lights. Though we think you will find it with a simple check pending it is not in the truck harness. And we assume you have verified that already. BCB
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