When it comes to boat trailer wiring it's a good idea to check to make sure all your lights are working before you hit the road. Usually your troubles are light fixture or bulb related failures mainly due to corrosion or backing hot bulbs into cold water. Use the handy reference charts I provided to make sure your wiring is correct. Always make water proof connections and I recemmend soldering and heat shrinking the connection for reliability. If you have hydraulic surge brakes and are having trouble backing up read my tip on brake solenoids here. If you encounter multiple problem areas with your boat trailer wiring it is far easier and less costly to replace the harness as a whole. They are available in a local boat accessory store for about $25.00. Take your time and make good repairs, look for pinched or corroded wires and your lights will be much less likely to leave you in the dark. If your wiring along with your axles, springs and maybe tires need serious attention maybe check out a new trailer at Boat Trailer Outlet.