How to Do Utility Trailer Wiring | Gone Outdoors | Your How to Do Utility Trailer Wiring by Michael Logan . Motorcycles on a Small Utility Trailer. Utility trailers come in various widths, sizes and load capacities. How a trailer is wired depends on what is required. Small trailers have side marker lights, tail lights, brake lights and turn signals. Trailers wider than 80 inches are required to have Trailer Wiring Diagram For 4 Way, 5 Way, 6 Way and 7 Way The red and blue wire can be used for brake control or auxiliary. Use on a small motorcycle trailer, snowmobile trailer or utility trailer. Can also be used as custom wiring on trailers with 3 light/wire systems. See "Tow Vehicle Taillight Wiring" below.