7 Trailer Wiring Diagram: A Comprehensive Guide

Whether you are towing a boat, utility trailer, or camper, understanding how to wire your trailer is important. Wiring your trailer safely and correctly can prevent accidents and ensure your lights, brakes, and other systems work properly. In this article, we’ll discuss 7 trailer wiring diagrams that cover most trailer types on the market.

Trailer Wiring Basics

Before we dive into the different wiring diagrams, let’s review some trailer wiring basics:

  • Trailer wiring is color-coded.
  • The colors on the wires match the functions they perform.
  • There are four or seven wires depending on the type of trailer.
  • The standard trailer wiring configuration is essential to know.

Now, let’s take a closer look at the seven different trailer wiring diagrams:

4 Pin Trailer Wiring Diagram

The 4-pin trailer wiring diagram is the most common wiring configuration for small trailers. It uses four wires, which consist of:

  • Yellow wire: Left turn signal and brake light.
  • Green wire: Right turn signal and brake light.
  • Brown wire: Tail lights and running lights.
  • White wire: Ground wire.

Here’s how to wire a 4-pin trailer:

Wire Color Function Trailer End
Yellow Left Turn Signal/Brake Light Connect to Left Trailer Light
Green Right Turn Signal/Brake Light Connect to Right Trailer Light
Brown Tail Lights/Running Lights Connect to Tail Lights
White Ground Connect to Trailer Frame

If your trailer doesn’t have brakes, you can leave out the yellow and green wires.

FAQ

Q: Can I use a 4-pin connector on a 7-wire trailer?

A: No, a 4-pin connector is only suitable for trailers without brakes. If your trailer has brakes, you will need at least a 5-pin or a 7-pin connector.

5 Pin Trailer Wiring Diagram

The 5-pin trailer wiring diagram is a custom wiring configuration used on some small boat trailers. It uses five wires, which consist of:

  • Brown wire: Right tail light.
  • Yellow wire: Left turn signal and brake light.
  • Green wire: Right turn signal and brake light.
  • Blue wire: Brake controller output.
  • White wire: Ground wire.

Here’s how to wire a 5-pin trailer:

Wire Color Function Trailer End
Brown Right Tail Light Connect to Right Trailer Light
Yellow Left Turn Signal/Brake Light Connect to Left Trailer Light
Green Right Turn Signal/Brake Light Connect to Right Trailer Light
Blue Brake Controller Output Connect to Brake Controller
White Ground Connect to Trailer Frame

The blue wire is not always present on 5-pin connectors, it depends on the wiring configuration of the trailer and towing vehicle.

FAQ

Q: Can I use a 5-pin connector on a 7-wire trailer?

A: Yes, you can use a 5-pin connector on a 7-wire trailer by leaving out the blue wire and the electric brake controller. However, if your trailer has electric brakes, we recommend using a 7-pin connector.

6 Pin Trailer Wiring Diagram

The 6-pin trailer wiring diagram is used on some larger trailers, such as horse trailers or enclosed trailers. It uses six wires, which consist of:

  • Brown wire: Right tail light.
  • Yellow wire: Left turn signal and brake light.
  • Green wire: Right turn signal and brake light.
  • Red wire: Reverse light.
  • Black wire: Battery charge input (utility trailer only).
  • White wire: Ground wire.

Here’s how to wire a 6-pin trailer:

Wire Color Function Trailer End
Brown Right Tail Light Connect to Right Trailer Light
Yellow Left Turn Signal/Brake Light Connect to Left Trailer Light
Green Right Turn Signal/Brake Light Connect to Right Trailer Light
Red Reverse Light Connect to Reverse Lights
Black Battery Charge Input (Utility Trailer Only) Connect to Battery
White Ground Connect to Trailer Frame

If you are using a horse trailer, you may also have a blue wire for electric brakes.

FAQ

Q: Can I use a 6-pin connector on a 7-wire trailer?

A: Yes, you can use a 6-pin connector on a 7-wire trailer by leaving out the black wire. However, if your trailer has a battery, we recommend using a 7-pin connector.

7 Pin Trailer Wiring Diagram

The 7-pin trailer wiring diagram is the most common wiring configuration for larger trailers, such as campers, RVs, and cargo trailers. It uses seven wires, which consist of:

  • Brown wire: Right tail light.
  • Yellow wire: Left turn signal and brake light.
  • Green wire: Right turn signal and brake light.
  • Blue wire: Electric brake.
  • Black wire: Battery charge input.
  • Red wire: Reverse light.
  • White wire: Ground wire.

Here’s how to wire a 7-pin trailer:

Wire Color Function Trailer End
Brown Right Tail Light Connect to Right Trailer Light
Yellow Left Turn Signal/Brake Light Connect to Left Trailer Light
Green Right Turn Signal/Brake Light Connect to Right Trailer Light
Blue Electric Brake Connect to Brake Controller
Black Battery Charge Input Connect to Battery
Red Reverse Light Connect to Reverse Lights
White Ground Connect to Trailer Frame

If your trailer doesn’t have electric brakes, you can leave out the blue wire.

FAQ

Q: Can I use a 7-pin connector on a 4-pin trailer?

A: No, a 7-pin connector is not suitable for a 4-pin trailer. You will need to re-wire the trailer with a 4-pin connector or install an adapter to match the wiring configuration.

7 Way Trailer Plug Wiring Diagram

The 7-way trailer plug wiring diagram is another common wiring configuration for larger trailers. It uses seven wires, which consist of:

  • Brown wire: Right tail light.
  • Yellow wire: Left turn signal and brake light.
  • Green wire: Right turn signal and brake light.
  • Blue wire: Electric brake.
  • Black wire: Battery charge input.
  • Red wire: Reverse light.
  • White wire: Ground wire.

The difference between the 7-way trailer plug and the 7-pin trailer plug is the shape of the connector. The 7-way plug has a rectangular shape, while the 7-pin plug has a circular shape.

Here’s how to wire a 7-way trailer plug:

Wire Color Function Trailer End
Brown Right Tail Light Connect to Right Trailer Light
Yellow Left Turn Signal/Brake Light Connect to Left Trailer Light
Green Right Turn Signal/Brake Light Connect to Right Trailer Light
Blue Electric Brake Connect to Brake Controller
Black Battery Charge Input Connect to Battery
Red Reverse Light Connect to Reverse Lights
White Ground Connect to Trailer Frame

FAQ

Q: Is a 7-way trailer plug better than a 7-pin trailer plug?

A: No, both plugs have the same wiring configuration, and their function is the same. The difference is in the shape of the connector, which may affect the ease of use and durability.

Auxiliary Trailer Wiring Diagram

An auxiliary trailer wiring diagram is used to power accessories or charge batteries while towing. It uses seven wires, which consist of:

  • Brown wire: Right tail light.
  • Yellow wire: Left turn signal and brake light.
  • Green wire: Right turn signal and brake light.
  • Blue wire: Electric brake.
  • Black wire: Battery charge input.
  • Red wire: Reverse light.
  • White wire: Ground wire.

Here’s how to wire an auxiliary trailer:

Wire Color Function Trailer End
Brown Right Tail Light Connect to Right Trailer Light
Yellow Left Turn Signal/Brake Light Connect to Left Trailer Light
Green Right Turn Signal/Brake Light Connect to Right Trailer Light
Blue Electric Brake Connect to Brake Controller
Black Battery Charge Input Connect to Battery
Red Reverse Light Connect to Reverse Lights
White Ground Connect to Trailer Frame

You can use the auxiliary trailer wiring diagram to add lights or charge batteries on your trailer.

FAQ

Q: Do I need an auxiliary trailer wiring diagram?

A: It depends on whether you need to power accessories or charge batteries while towing. If you don’t need to do either, you don’t need an auxiliary trailer wiring diagram.

Conclusion

Now that you have a better understanding of the different trailer wiring diagrams, you can choose the one that is right for you. Remember to always follow the wiring instructions carefully and double-check your connections for safety. If you are unsure about anything, consult a professional.