How to Install Trailer Wiring
Why is trailer wiring so important? Because it's the law! If you’re going to tow a trailer, you need your trailer lights to be connected to your vehicle. When you turn your left turn signal on for your vehicle, the one on your trailer needs to come on. Trailer wiring is a simple connection that enables everyone’s safety on the road.
There are multiple options for installing trailer wiring on your vehicle. Quick Connect wiring kits are the most popular choice because they each use a plug-and-play harness that easily connects to your specific vehicle. Other options include Universal Wiring kits or replacement plugs and sockets.
If you'd prefer that a hitch professional handle your trailer wiring installation, schedule a visit with U-Haul by visiting the online reservation page or by downloading the U-Haul App.
Otherwise, when connecting wiring from a vehicle to a trailer yourself, it's important that you follow a specific color code to be sure that signals are not crossed.
Trailer Wire Color Codes
What is the color code for trailer wiring? Each wire of the trailer wiring serves a purpose as mentioned before; one for taillights, one for the left brake light, and one for the right. Following the color code is important because mismatched wires will lead to confusion on the road if the trailer lights won’t function properly.
The 4-way flat trailer-wiring harness is commonly used and only uses four colors, thus the 4-pin name. There are also 5-, 6-, and 7-pin trailer wiring harnesses that come in flats, rounds, and squares.
4 Pin Trailer Wiring
The 4-pin trailer is the standard for trailer wiring. Most utility trailers operate on a 4-pin trailer plug for the safety of your vehicle while towing. For the 4-pin, the green wire is for the right turn/brakes, the yellow wire for the left turn/brakes, brown is for the taillights, and white is for the ground.
4 Pin Trailer Wiring Diagram
5 Pin Trailer Wiring
The 5-pin trailer wiring is not as common as the 4-pin but its fifth function is very important. Typically the fifth wire added is a blue wire, which with the use of a 5-Way Flat will show the reverse or backup lights. Not all trailers have reverse lights, using 5-pin wiring depends on if you need it. Boat trailers commonly use 5-pin wiring.
5 Pin Trailer Wiring Diagram
6 Pin Trailer Wiring
For heavier towing jobs, many use gooseneck trailers. Those are generally put in the bed of a truck and use a 6-pin trailer wiring adapter. 6-Pin trailer wiring uses the same color code as 4- and 5-pin trailer wiring, adding one more function. This wire is black and adds auxiliary power. Most 6-pin wiring is rounded.
6 Pin Trailer Wiring Diagram
7 Pin Trailer Wiring
The 7-pin trailer wiring is used mostly for RVs and heavy items. There are many types of 7-pin wiring kits. The colors and functions can vary, be sure to check what color means what before connecting your wiring. We recommend using the 7-Way Spade Type & 4-Way Flat Connector because it provides 7-way round and 4-way flat towing from one location.
7 Pin Trailer Wiring Diagram
U-Haul Trailer Wiring
If trailer wiring isn’t your thing, let U-Haul handle it. U-Haul is North America's #1 hitch installer. With over 1,500 install locations, we can guarantee you'll find a location near you. Tell us your vehicle year, make, and model and we will show you available trailer hitches and related towing components. We also have an extensive selection of wiring as well as ball mounts, hitch balls, trailer accessories, and other towing components to help you get on the road and towing. U-Haul also offers truck and trailer rentals for your towing needs. Reserve yours today.