When I attach my traylor without connecting the wire harness the traylor lights come on. What's going on here

Hi, this is more about knowing what powers your trailer lights than It is your vehicle. If there's nothing electrical hooked up to the trailer at all, I'm at a loss as to what could provide it power to turn lights on -- unless there's some kind of on board power from the trailer itself. Consult the information for the trailer for more trailer info. This does not appear to be a vehicle issue. It's impossible to know what is going on without first hand knowledge of the equipment in play. You may need to consult a shop near you for guidance, hands on.

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