Auto Tips: How To Wire A Trailer For Pulling

Wiring a trailer to a tow vehicle is easily accomplished following a few simple steps.

Wiring a trailer to a tow vehicle provides lights and often brakes for the trailer. This increases the safety aspect of towing a trailer and is a law in most states. Wiring a trailer to a tow vehicle is easily accomplished following a few simple steps.

Trailers should be wired to code, meaning that each colored wire represents a part of the system. Green is the right turn signal and brake light, yellow is the left turn signal and brake light, orange is the tail or marker lights, white is the ground wire, red is the auxiliary power wire, blue is the electric brakes and pink is the backup lights. These colored coded wires correspond to trailer plugs that make them interchangeable. When wiring a trailer be sure to wire each object with the correctly colored wire so that they are up to code and the plugs will be interchangeable with different tow vehicles. Run the correctly colored wire from the plug located on the tongue of the trailer to the corresponding object on the correct side of the trailer and connect both ends, one to the object and the other to the plug. Repeat the procedure until all objects are wired, then securely attach the wires to the frame of the trailer to protect them.

There are many different styles of plugs, from flat ones to small round 4-way conductors all the way to 9-way trailer applications. The most commonly used plugs are the 4-way, 5-way, 6-way and 7-way connectors.



The flat plug is commonly a quick set-up used on smaller trailers and SUV's. This plug uses white, yellow, orange and green wires and will allow both the right and left turn signals and brake lights to work as well as the tail lights and running lights and of course, a ground wire.

A 4-way plug is excellent for heavy-duty power requirements, which usually means many lights such as the turn signals, brake lights, taillights, running lights and a ground wire are needed.

5-way plugs, though rarely seen, do occur occasionally. The fifth lug located on this plug is for trailer brakes.

The most commonly used and generally considered universal is the 6-way plug. Car trailers, large utility trailers and virtually all other trailers that use trailer brakes and auxiliary power, often including small travel trailers will have these plugs. 6-way plugs have one larger lug, added for higher amp demands and like other plugs contain labels on the inside with the code for each lug. The installer connects the corresponding wire to the correct lug. These abbreviated codes are R/T (right turn), L/T (left turn), T/M (tail/marker), Gd (ground), Bk (brake) and B/U (back up).

The 7-way trailer plug is the one used for heavy-duty trailers such as big travel trailers and large racecar haulers. This plug allows all the wires mentioned above to be connected to corresponding lugs that are large enough to carry the load. The lugs in these plugs are large enough to carry huge amp draws often found on these trailers such as winches and battery chargers. Even though these plugs are tough, they require more maintenance, are harder to keep clean, and corrosion free.

Most trailers are required to have at least running lights, turn signals and brake lights for safety reasons. Wiring a trailer for these lights is not difficult with the right instructions, but if you are in doubt get a professional to do the wiring.

© High Speed Ventures 2011