5 flat wiring connector will still work. It may be to just connect the trailer lights on your vehicle or you may find yourself rewiring the whole trailer with new led boat trailer lights and a new wire harness.

29 Wiring Diagram For Trailer Light And Brakes Trailer
Wiring for a boat trailer. Two types of a trailer wiring tester. Hook up your trailer and connect the trailer light harness. If all the lights appear dim or you have no lights at all check the trailer light harness at the tow vehicle. The fifth wire is hooked up to the reverse light circuit on the vehicle which then sends a signal. The 5 way flat trailer connector is most commonly found on boat trailers that have hydraulic brakes. Fresh wires do wonders for your boat trailer lights.
Wiring a boat trailer is something that many boaters find themselves needing to do sooner or later. Though led lights have reduced failures trailer wiring still causes diy boaters fits especially when trying to fix a short at the launch ramp before leaving for home at dusk. Its an axiom among trailer boaters that once you fix an annoying problem another one seems to crop up quickly invariably the night before you head for the water. Have a helper stand back to see if the running lights stoplights and blinkers are working properly. Here are six key tips to make your boat trailer wiring job hold up over time. 5 flat electrical wiring connector fifth wire added for surge brake lockout circuit which is becoming more common on todays newer boat trailers.
Few things prove more frustrating than troubleshooting trailer lights. Check your vehicles plug configuration. Six tips for rewiring your boat trailer west marine.