Trailer Wire Color: The Definitive Guide

This article is a guide on which wire colors are essential for safety incentives in trailers. The lights must work, and the electricity has to be strong enough to power all parts of the trailer, as well as provide brake lights, turn signals and tail lights. All breaks have to be electrified too, otherwise they will stop working with time.

Whether you want to change the wiring system of a trailer or improve the brake functions, wire colors are an important part of this process. This article will show you different wire colors and will help you pair them with their function.

Trailer Wire Color Guide: Introduction

A guide is necessary when you have a need for a reminder of the basics. The basics include 4-pin, 5-pin, and 7-pin connectors and the meaning of each wire color in the wiring systems. There are no ideal wires across different standards, but all serve their own unique purpose.

In this guide, you’ll find basic knowledge on wiring your trailer and understanding the diagrams supplied by your wire supplier. There are universal standards for wiring, which will work on most trailers; however, you’ll still need to follow the diagrams given to you by your individual supplier. But if you want a summary understanding of how each connector works, follow the guidelines below.

Read about 4 core wire installation

The most basic trailer connector is the 4-core connector. This connector is easy to install and use because it only needs 4 functions: left, right, taillights, and brake lights connected with a 4-wire connector.

The 4-pin connector is a popular choice among smaller trailers because it is easy to install. For example, camper trailers and tiny boat trailers use this type of connector.

You can also find two connectors of this kind, one with a round shape, and one with a flat shape. The common connector is the flat 4-pin connector that is mainly used in moving and stationary trailers.

Learn the four core trailer wire colors and their meanings

Individual wires need to be connected one by one and the different colors represent different things.

• 1) The white color signifies the ground.
• 2) The brown color indicates tail lights or possible side markers.
• 3) The yellow color implies a left turn signal light.
• 4) The green color means a right turn signal or light.

5 Core Trailer Wire: Installation

The 5-core trailer wire is popular on heavier trailers, and those that exceed 3000 lbs in weight. These cables need to have breaks to ensure braking efficiency, and the 5-core cable provides the extra connectors necessary. States may have variations in laws, but it’s always a good idea to install brakes on trailers too heavy for the wires provided by such laws.

Installing brakes on your trailer preserves a safe speed and reduces its effects on the environment. The installation process is rather simple and only needs 5-core wire because they break when weight exceeds a certain amount.

You need at least a 5-pin connector wire to install breaks. The 5-pin connector has one additional blue wire. This gives drivers the power to operate breaks.

The 5 most common colors and their meanings in your trailer wire

Connecting a 5 core electrical connector is time consuming and confusing. The wires have different purposes and need to be connected individually.

• 1) The white color signifies the ground.
• 2) The brown color means tail lights or possible side markers.
• 3) The yellow color indicates a left turn signal light.
• 4) The green color signifies a right turn signal or light.
• 5) The blue color suggests electric breaks or hydraulic release.

If you need to use less than 5 pins for your 7-core plug, you can just leave the 2 pins out. Similarly, if there are 2 unused pins on a 7-pin socket, then you can use the other ones.

If you’ve stumbled upon this situation, all you have to do is remove your original wires and connect them with a 5-pin wire. This will make the wires compatible with your trailer. There are ways to get around this problem, like removing cables if you know they’re incompatible.

7 Core Trailer Wire: Installation

The 7 core trailer wire is the largest set of wires you can purchase for a trailer. It provides light and break services, and is recommended for large trailers such as RVs or trailers that people could live in.

If you have a trailer that has a lot of electronics, use the 7-core trailer wire which provides adequate signaling.

7-pin wire connectors are similar to the 4 and 5-pin connectors but they also include backup lights and power. The 7-pin connector is a bit more complex, but the connection principles are the same.

Industrial standards for the 7-core connectors are the same, meaning that you can interchange the wires. Remember that when 7-core connectors have a different shape and 5-core connectors don't. 7-core connectors give you an option to use extra wires for power, back-up lights, or to not use them at all.

7-Core Trailer Wire Colors & Meaning

A 5-pin connector consists of five wires that need to be connected one by one. The trailer wire colors correspond to different meanings depending on their place on the connector.

• 1) The white color signifies the ground.
• 2) The brown color means tail lights or possible side markers.
• 3) The yellow color indicates a left turn signal light.
• 4) The green color shows a right turn signal or light.
• 5) The blue color signifies electric breaks or hydraulic release.
• 6) The red color implies auxiliary power (usually 12V power).
• 7) The purple color suggests back-up lights. This color may vary based on the manufacturer.

Trailer Wire Size & Connection

Trailer wires come in three gauges, with the least common of these being 16-gauge. The 14 and 12 gauge wires are more commonly used, but the minimum requirements for powering a trailer could be fulfilled with a 12 or 14 gauge wire if LEDs are used which require less power.

For large, 5-core or 7-core connectors that require a more powerful brake system, we recommend the 16-gauge wire size. As compared to 12-gauge wire, the 16-gauge is thicker and more robust. The small difference in price is justified for the peace of mind it provides you on the road. However, if you want to save some money you can always go with 12-gauge wire instead.

Although your trailer is not a boat and isn't subjected to water very much, you need protection from moisture when you do engage in activities near water. Submersible LEDs can help with this as opposed to non-waterproof LEDs.

Trailer Wire Color Signify

This is the universal way you should connect each color wire to the same pins on all trailers. If a red wire touches a green or a black wire, it can create an electric shock with the potential for death.

1) White Wires

The first wire you need to connect is the ground/negative wire. This wire needs to go directly to the lights and breaks.

The largest or biggest wire must be the white; otherwise, all of your accessories will have electrical issues. You should connect the device's ground to the mainframe and then connect the trailer's mainframe to the ground.

Connecting the white wire to each light ensures that no need for repairs down the line. You will require a large wire for additional auxiliary power needs.

2) Brown Wires

The brown wire is used to connect the front running lights and the small segment of taillights with the corner markers. This wire can also be used to connect the three central lights on the back of the trailer.

If you have a small trailer and it needs 3 headlights, you can connect them easily by following these directions. You'll be able to attach the brown wire to the lights and the white one to ground.

In terms of size, the wire has to be proportional to the size of your trailer, and it is not necessary for it to be oversized. You need to check the power requirements of your LED bulbs in order to determine what size you will need. If you have an RV trailer with a large power requirement, you may need a larger brown wire, however if you have a smaller RV trailer with few power needs for LED bulbs, you can use a smaller one instead.

3) Blue Wires

The blue wire is responsible for the brake system and reverse lights of the car - sometimes it can be used to control the reverse lights of a trailer using hydraulic brakes. To do this, connect it to the reverse lights of the vehicle.

When wiring a trailer's brakes, we recommend you use 16 gauge or higher blue wire. When making connections to the brake controller, not all "blue wires" are the same.

4) Red Wires

The 7-core connector is red. The wire that's responsible for the auxiliary power is also red and provides access to the positive power of the vehicle. It powers all inside lights, trailer accessories, and more.

If you want to take advantage of your trailer's separate power source, then make sure you follow these instructions on how to install and wire separate power. The size of the wiring should be big enough so that it can handle the vehicle.