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Know Trailer Wiring Diagram & Trailer Connector Installation – Tirol

Trailer Connector

Have you ever used the trailer connector wiring? Connector pins have different colors. That makes it difficult to understand the right color for a specific pin.

Different trailer wires of a variety of colors can be confusing. We’re here to guide you on the trailer wiring and connector installation.

Having trailer wiring connectors that are compatible with your vehicle can help you in towing. For safe towing, you need connector pins. These pins are connection points between the vehicle and the trailer. It makes towing easy.

You’ll not even have to put much effort into moving the damaged vehicle. That’s why it is important to choose the right trailer connectors and install them correctly.

Trailer Wiring Diagram

When towing a vehicle, trailer wiring is important. It’ll not only connect the signal or brake lights but also avoid issues in the electrical system. If your vehicle doesn’t have a trailer wiring connector, you can still equip the vehicle with it.

If your trailer doesn’t have wiring, do it now. It’ll keep the vehicles safe on the roads. You’ve to connect the right color code with the trailer plug.

Trailer wiring is important because it helps to:

  • Connect rear light
  • Connect brake lights
  • Set up electrical systems

What wiring you’re doing depends on the electrical system. For driving the trailer, you need power on lights and activated electric brakes. That’s why you need a proper wiring diagram.

Typical Trailer Wiring Diagram and Schematic

Trailer wiring

A trailer has two axles: a single axle and a tandem axle. The wiring for these axles is the same; except for the blue and white wire.

You should use the wires you need. Axles with brakes must have the right pin wiring. However, wires without brakes can be left blank. Also, be sure not to change the position of the wires. Adjust the right colored wire in the correct pin connector.

Wire Routing

You’ll know what to do with the wiring. When routing wires into the connector, it should have a covering. The wire covering includes a plastic conduit. It protects the wiring from harsh weather conditions. Also, preventing from affecting the splice-in wires.

Trailer Connector Introduction

Do you want to know the towing capacity of your vehicle?

You can use connectors to tow the vehicle. You’ll use trailer connectors of different sizes and configurations. This depends on your trailer. Before buying, you should know which connector is suitable for your trailer.

Apart from this, connectors are important to carry the trailer from one place to another. It keeps the towing safe and effective. Thus, you’ve to build connection points between the vehicle and the trailer.

Classification Of Trailer Connectors

Trailer Connectors

You can read the types of connectors and find the best fit for your vehicle.

4-Pin Connector

There are a minimum of 4 pins that can connect to the trailer. The connection of the 4-pin is simple. It’s because these are lighter and have no brakes. You’ll find 4-pin connectors lightweight. That’s what makes it of common use.

These 4 functions include:

  • Brake Light
  • Rear light
  • Left signal
  • Right signal

This is a 4-pin connectors color code chart:

Connector Pins Color Function
1 White Ground
2 Brown Powers ON Rear light
3 Yellow Right Signal & Brake light
4 Green Left Signal & Brake light

You can use this connector for trailers that carry passengers. For example: campers, off-road vehicles, and boats.

5-Pin Connector

The first four pins are standard connectors. However, the fifth one is not common for all trailers. A trailer without brakes uses four pins. On the other hand, traditional trailers have brakes. Therefore, these connect five pins to the vehicle.

Using the 5th pin is important. It provides enough power to the brakes. Also, when reversing the vehicle, the pin stops the brakes from working.

You can see this trailer wiring chart below to know the use of 5 pins.

Connector Pins Color Function
1 White Ground
2 Brown Powers On Rear light
3 Yellow Right Signal & Brake light
4 Green Left Signal & Brake light
5 Blue Disables electric or hydraulic brakes

6-Pin Connector

There’s an addition of two pins in a four-pin connector. It makes a 6-pin connector for more purposes. These functions include brake controllers and a 12 Volt auxiliary power. You’ll find 6-pin connectors available for horse vans, campervans, and coaches.

Connector Pins Color Function
1 White Ground
2 Brown Powers On Rear light
3 Yellow Right Signal & Brake light
4 Green Left Signal & Brake light
5 Blue Brake Controller
6 Red 12 Volt Power

7-Pin Connector

When it’s about more electric vehicles, 7-pin connectors are the best choice. The additional pins provide power and help to back up lights. For example, trucks, vans, or big trailers. In some cases, you might not have an aux power of 12 V, but have backup lights. You can still use a 7-pin connector and leave one or two wires unconnected. There’ll not be any problem in leaving the pins blank.

Connector Pins Color Function
1 White Ground
2 Brown Powers ON Rear light
3 Yellow Right Signal & Brake light
4 Green Left Signal & Brake light
5 Blue Disables electric or hydraulic brakes
6 Red 12 Volt Accessory Power
7 Purple Backs up tail lights

There are two types of pins: flat pins and round pins. Flat pins are also named blades. It is a common choice. However, round pins are not often used.

You have to choose a pin connector that fits best with your trailer. If you need a 5-pin connector but do not find this one. You don’t have to worry. You can use a 7-pin connector. It is not important to get the standard connector. Leaving two or more wires or pins unused doesn’t matter.

Points To Be Noted

Note these points before finding the wiring system for your trailer:

Wire Size

There are different sizes of wires. The larger wire is thinner, while the small wire is thicker. We recommend using a 12 or 14-gauge wire for brakes. While a 16 gauge wire is better for lighting.

In addition, you should use a small gauge wire for low-power lights. However, a 16 gauge wire is larger, and controls high-power LED lights. It also helps in splicing.

LED Power Lights

Your trailer should have high-quality lights. So, they are long-lasting. During heavy rain, lights get damaged. Therefore, get sealed lights. These are worthy. Helping prevent any trouble when washing.

Wiring Color Code Guide

You should know the meaning of different colored wires. That helps you to fit the right color in a specific pin number.

White Wires

These wires are the main wires used for grounding. It also refers to negative wires. White wires have a connection with the lighting system and vehicle brakes. You’ll have to connect the ground to the white wire through the lights.

You should get a larger wire to avoid electrical issues. Besides, a wire supplying auxiliary power is also important.

Brown Wires

This wire deals with the front and rear lights. It supplies power to the running lights. If you haven’t observed, these wires stay on when driving the vehicle. Brown wires connect to all the running lights. When buying a brown wire, you should consider the following:

  • Trailer’s size
  • LED lights power

If the light bulbs use less power, a small wire is enough. But trailer lights with greater power require large wires.

Yellow & Green Wires

Whenever you turn your signals, the right and left lights activate. Even these lights turn on when applying brakes. The yellow wire deals with the left turn, while the green wire controls the right turn lights.

Depending on the power of LED lights, you choose the size of the wire. However, a 16 gauge wire is a good option.

Blue Wires

When it’s about controlling brakes, blue wires play an important role. It also deals with the brake lights at the back of the vehicle. You have to connect the blue wires with the reverse brake lights. You should use a 12 or 14-gauge blue wire.

Red Wires

The vehicle’s lights turn ON when you supply power. For this, you can use red wires. These include a 7-pin connector. It provides auxiliary power to all the lights and electrical components of the trailer. Though, the 7-pin connector is a power supply wire, so it should be bigger. Since it’ll handle the vehicle’s system.

Apart from this, you can also use a separate power source for the lights. But you should know how to install it.

Trailer Connectors For Vehicles

When you have to tow a trailer, you’ll need a trailer connector. You have to check if the connector is compatible with your trailer or not.

Here is which vehicle requires what type of connector pins:

Vehicle Type Trailer Connector
Truck or SUV 7 pin
Minivan 5 pin
Cargo trailer 4 pin

Mostly, these trailer connectors are attached to the vehicle’s backlights. Some connectors fit inside the trunk. This wiring system is near the hitch ball.

How To Install Trailer Connectors?

Install Trailer Connectors

Do you know how to install the trailer connectors properly? If not, you’ll have the know-how now.

Installing the trailer connectors is simple and easy. You don’t require much equipment to fit the wiring system. Just get the wires, lights, and electrical components. Here is how to install the pins at the connection points of your trailer. Follow the guide below:

Custom Wiring

Every vehicle needs a standard trailer connector to ensure safe transport. Custom wiring is considered the ideal installation method. It’s because you don’t have to splice the wiring. You use trailer connectors, such as a 4-pin connector, and plug in the blank spot of your vehicle.

Furthermore, custom wiring requires trailer connectors, plugs, and electric converters. These components help to install connectors.

Types Of Custom Wiring

There are two types of custom wiring for installation. You can use any one of them.

Custom Wiring Harness

At first, you install the plugs into the rear lights portion. It pulls out the power from the battery and provides you with a trailer wiring connector. You don’t have to splice or solder wires.

Custom Wiring Connectors

Most of the vehicles do not have a wiring connector to connect the pins. However, they have sockets to install the wiring in it. You have to place the plug in the socket space. This will act as a trailer wiring connector.

Install Trailer Connectors


Some vehicles might not have a trailer wiring connector. When there’s no trailer connector, you need an electrical converter. The electrical converter is also known as the taillight converter. This electrical converter creates a wiring connection in the vehicle. You can do this by splicing.

You have to splice the vehicle’s wiring to provide a standard trailer wiring connection. This standard wiring connector is a flat 4-pin one. It splices the vehicle’s wiring such that it fits into the trailer’s wiring.

Replacement Plug Wiring & Sockets

If the trailer wiring connectors get damaged, you splice to fix them. Sometimes, when you’re towing the vehicle the connectors can stop working. For this, you’ve to replace the wiring connector. And fit the plug or socket using the splice-in technique.

In addition, you should adjust the plugs in your trailer’s connectors. And connect the sockets in the vehicle. You will get these replacement parts in different shapes and sizes. You have to get the one that is compatible with your vehicle and trailer. So, there’s no issue while towing.

Replacement Plug Wiring & Sockets


You have to connect the trailer wiring for towing. Wherever you’re going camping, you can carry your camping site with the vehicle. And that’s possible through connectors.

Tirol makes your driving and towing easy as well as safe. We have all kinds of trailer wiring of different sizes. You have to use trailer connectors to keep the vehicles stable and safe during towing.

Read the guide above to know the trailer wiring and connector installation process. If you still don’t understand which connector pin to install or how to install it, you can send the inquiry to our email.



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