Trailer Connector Wiring Diagrams

Learn how to install or repair a Trailer Connector using these Trailer Connector Wiring Diagrams

If you’re wiring in a trailer connector from scratch, the connector you choose depends on the lights on your trailer. If your lights have reverse (backup lights) or electric trailer brakes, or an auxiliary power socket, you’ll need a connector with more wires. These trailer connector wiring diagrams cover the vehicle and trailer side views starting with the simplest 4-wire designs all the way up to the 7-wire designs.

At the very least, you need a minimum of four wires to meet the basics of trailer wiring

Left turn
Right turn
Brake lights
Ground for all of the above

Trailer wire color standards

GREEN is used for the right turn signal
YELLOW is used for the left turn signal
BROWN is used for tail/parking lights
WHITE is used for the ground connection

Two type of 4-wire trailer connectors

The 4-wire connectors provide brake, parking, and left and right turn signals. The flat connector is the most common connector.

Choose from two types of 4-wire connectors: flat and round.

4-wire connector trailer connector wiring diagrams for flat and round connectors

5-wire trailer connector wiring diagram

The blue 5th wire in this configuration is used for electric trailer brakes, however, or as a power supply for accessories.

Electric brakes are no mandatory in every state. But it’s recommended for trailers with a  3000-lbs Goss Trailer Weight

6-wire trailer connector wiring diagram round connector

The 6-wire connector allows you to power electric brakes and auxiliary power. If the vehicle is pre-wired, follow the purpose of the center wire.

7-Wire Round Connector

A 7-pin plug is referred to as a 7-way trailer connector.

The connector is a 2-in. diameter plug and receptacle used on heavy-duty trailers.

There are two types of 7-wire connectors; pin and blade style, and three wiring pinouts. This image shows the wiring diagram for a 7-wire PIN style trailer connector. Below this section you’ll find the 7-wire BLADE style with the SAE wiring diagram, and below that you’ll find the 7-wire BLADE style using the RV wiring diagram.

These connectors and wiring diagrams are not interchangeable!

7-Wire Round BLADE Connector SAE

7-Wire Round BLADE Connector RV Configuration

WARNING: Your vehicle may have been wired differently from the factory or it may have been modified by the previous owner or by a shop. Always double-check factory wiring and compare tho these diagrams before hooking up your trailer.

©, 2024 Rick Muscoplat