Check your tow vehicle plug first with a 12V tester make sure the plug works..... some TVs have separate fuses for the trailer plug....... When I have problems I run a separate ground wire from the TV to the Trailer.......... That's the first steps I always take then I move on to checking the trailer............. I currently own 4 utility trailers & the fiver & have for years....usually when I have troubles it is usually a ground but I did have a camper that would blow the TVs trailer fuse to the left side........next I move on to corrosion issues