How to Wire Trailer Brakes and Lights

When it comes to towing and hauling, a well-wired trailer is essential. Without proper knowledge of wiring a trailer, hauling may become dangerous due to unexpected malfunctions. Knowing how to wire a trailer brakes and lights can help the owner of a trailer be prepared and aware when towing their goods. This article will provide an overview of the basics of wiring a trailer brakes and lights, including detailing the types of connectors and instructions for wiring them.

Types of Connectors for Wiring a Trailer Brakes and Lights

The type of trailer connector must be compatible with the type of vehicle wiring system found in the towing vehicle, as well as being capable of handling the electrical current requirements of the trailer’s devices. When wiring a trailer brakes and lights, there are four common types of trailer connectors on the market, including 4-pin, 5-pin, 6-pin, and 7-pin connectors.

4-Pin Connectors for Wiring a Trailer Brakes and Lights

The 4-pin connector is the most commonly used trailer connector, mostly because of its versatility. It has four pins; the basic function of the four pins are left turn/brake, right turn/brake, tail/marker lights, and ground. This type of connector is suitable for many smaller trailers, such as utility and small boat trailers, which typically connect the running light system of the vehicle to the taillights and brake functions of the trailer.

5-Pin Connectors for Wiring a Trailer Brakes and Lights

The 5-pin connector includes all of the wires found in the 4-pin connector, plus an auxiliary power wire to supply power to the trailer brakes. This extra power wire is used to activate the trailer brake system, typically a breakaway or surge brake system, allowing the trailer brakes to engage when the vehicle brakes are applied. This connector is used in larger trailers such as horse trailers, livestock trailers, and cargo trailers.

6-Pin Connectors for Wiring a Trailer Brakes and Lights

The 6-pin connector is identical to the 5-pin connector, except it adds a fifth wire to the connector to operate a backup light system. This allows the driver to see their trailer at night when backing up their trailer. The 6-pin connector is most commonly used on large travel trailers, campers, and fifth wheels.

7-Pin Connectors for Wiring a Trailer Brakes and Lights

The 7-pin connector is the largest trailer connector, designed to be used on large towing vehicles such as commercial trucks and buses. Unlike the others, the 7-pin connector allows for one or two additional circuits, including a connection for reverse lights and a connection for a 12V accessory.

Instructions For Wiring a Trailer Brakes and Lights

Before beginning the installation process, it’s important to check the towing vehicle and trailer for compatibility. The electrical systems of both the tow vehicle and trailer must match in order for the installation to be successful. Once the compatibility is confirmed, here are the steps for wiring a trailer brakes and lights:

Connect the trailer lights to the towing vehicle’s wiring harness.

Connect the trailer brakes to the trailer brakes' controller.

Connect the auxiliary power wire to the trailer brakes' controller.

Test the wiring with a multimeter.

Test brake functions and tail/marker lights manually.

Wiring a trailer brakes and lights is an essential skill for any trailer owner, and knowing how to properly do so can be the difference between a safe and successful towing experience, or a disastrous one. Following the instructions outlined above can make the wiring process much simpler and ensure that the trailer is properly wired and ready to go.

Neo Trailers Manual