Wiring Diagram 4 Wire Trailer

Hello readers, welcome to this informative article about the wiring diagram for a 4 wire trailer. In this piece, we will delve into the details of the wiring diagram, discussing its advantages, disadvantages, and alternative options. So, let’s get started!

1. Understanding the Basics of a 4 Wire Trailer Wiring Diagram

A 4 wire trailer wiring diagram is a schematic representation of the electrical connections required for a trailer. It consists of four wires, each serving a specific purpose:

Wire Color Function
Brown Tail Lights
Yellow Left Turn and Brake Lights
Green Right Turn and Brake Lights
White Ground

This wiring diagram provides the necessary information to connect the trailer’s lights and signals to the towing vehicle accurately.

2. Advantages of a 4 Wire Trailer Wiring Diagram

The 4 wire trailer wiring diagram offers several advantages:

  • Simplicity: With only four wires to connect, the wiring process becomes straightforward, even for beginners.
  • Compatibility: This standard wiring diagram is widely recognized and compatible with most trailers and towing vehicles.
  • Cost-Effective: The simplicity of the 4 wire system makes it cost-effective compared to more complex wiring setups.

3. Disadvantages of a 4 Wire Trailer Wiring Diagram

While the 4 wire trailer wiring diagram has its merits, it also has a few drawbacks:

  • Limited Functionality: The 4 wire system only supports basic lighting functions and does not accommodate additional features like electric brakes or battery charging.
  • Reduced Safety: As the 4 wire system lacks certain advanced functionalities, it may compromise safety in certain situations, such as when towing heavy loads.

4. Alternative Wiring Diagram Options

If you require additional functionalities beyond what the 4 wire trailer wiring diagram offers, you may consider alternative options, such as:

  • 5 Wire System: This wiring diagram includes an additional wire for electric brakes, allowing for improved safety and control.
  • 7 Wire System: The 7 wire system provides even more functionalities, including battery charging and reverse lights.

Frequently Asked Questions (FAQ) about 4 Wire Trailer Wiring Diagram

Q: Can I use the 4 wire system for a trailer with electric brakes?

A: No, the 4 wire system does not support electric brakes. You should consider a 5 wire or 7 wire system for trailers with electric brakes.

Q: How do I connect the wires based on the 4 wire trailer wiring diagram?

A: Connect the brown wire to the tail lights, the yellow wire to the left turn and brake lights, the green wire to the right turn and brake lights, and the white wire to the ground.


In conclusion, the 4 wire trailer wiring diagram is a simple and widely compatible solution for connecting a trailer’s lights to a towing vehicle. While it may lack advanced functionalities, it offers ease of use and cost-effectiveness. However, if you require additional features, considering alternative wiring diagram options like the 5 wire or 7 wire system is advisable. Ensure to follow the diagram accurately for a safe and reliable trailer towing experience.