How to Wire Lights on a Trailer | Wiring Diagrams Nov 21, 20185 wire trailer wiring diagram. 5 way trailer wiring diagram allows basic hookup of the trailer and allows using 3 main lighting functions and 1 extra function that depends on the vehicle: daytime running lights; turn signals; brake lights; an extra pin allows using another extra function.5/5(2)Author: Andrew Demaree How To Wire Lights in Parallel? Switches & Bulbs How To Wire Lights in Parallel? In the above fig, it is clearly shows that all the light bulbs are connected in parallel i.e. each bulb connected through separate Line (also known as Live or Phase) and Neutral wire.