12 Volt Trailer Light Wiring Diagram: A Comprehensive Guide

Having a trailer with functional lights is crucial for safe travels. However, wiring the lights of a trailer can be confusing and daunting, especially if you don’t have any prior experience with wiring. In this article, we will provide you with a comprehensive guide on how to wire your 12-volt trailer lights efficiently and safely.

What are 12-Volt Trailer Lights?

12-volt trailer lights are LED or incandescent lights installed on a trailer that is powered by a 12-volt DC battery. These lights are essential in providing visibility, especially when driving at night or in low light conditions.

Typically, 12-volt trailer lights include tail lights, brake lights, reverse lights, and turn signal lights. These lights should be wired properly to ensure that they function correctly and safely.

How to Install 12-Volt Trailer Lights

The installation process of 12-volt trailer lights can be broken down into the following four steps:

  1. Disconnect the trailer from the towing vehicle and remove the old lights (if any).
  2. Install the new lights according to the manufacturer’s instructions.
  3. Wire the new lights to the trailer’s wiring system.
  4. Test the lights to ensure they are functioning correctly.

Wiring Your 12-Volt Trailer Lights

Wiring your 12-volt trailer lights is not as complicated as it may seem. With the right tools and instructions, you can get the job done quickly and efficiently.

Tools Needed

Before you start wiring your trailer lights, gather the following tools:

  • Wire cutters/strippers
  • Tape measure
  • Wire connectors (butt/splice connectors)
  • Heat shrink tubing
  • Screwdrivers (Phillips/flathead)
  • Battery tester/voltmeter

Wiring Diagram

A wiring diagram is a visual representation of the trailer light wiring connections. It helps to ensure that all wires are connected to the correct terminals and that the lights function correctly.

12-Volt Trailer Light Wiring Diagram
Wire Color Function
White Ground
Brown Tail lights
Yellow Left turn signal
Green Right turn signal
Red Brake lights

Refer to the wiring diagram above for a more visual representation of how to wire your 12-volt trailer lights.

Step-by-Step Guide to Wiring Your 12-Volt Trailer Lights

Follow these steps to wire your trailer lights:

  1. Strip the insulation from the wires using wire cutters/strippers.
  2. Twist the ends of the bare wires together and insert them into the appropriate wire connectors.
  3. Crimp the connectors with pliers to secure the wires in place.
  4. Slide heat shrink tubing over the connectors and shrink it with a heat gun to create a waterproof seal.
  5. Connect the white wire (ground) to the trailer frame using a screwdriver.
  6. Connect the brown wire (tail lights) to the running light circuit on your vehicle.
  7. Connect the yellow wire (left turn signal) to the left turn signal circuit on your vehicle.
  8. Connect the green wire (right turn signal) to the right turn signal circuit on your vehicle.
  9. Connect the red wire (brake lights) to the brake light circuit on your vehicle.


Q: Can I use 12-volt car lights on my trailer?

A: No, car lights are not compatible with trailer lights. Trailer lights are designed to be waterproof and more durable, while car lights are not. Also, the wiring system on trailers is different from cars, so car lights may not fit or function properly.

Q: How do I know if my trailer lights are working?

A: To check if your trailer lights are working, connect your trailer to your vehicle and turn on the lights. Walk around the trailer and check if all the lights are functioning correctly. You can also use a battery tester/voltmeter to check if each wire is receiving the correct amount of voltage.

Q: How do I fix trailer lights that are not working?

A: If your trailer lights are not working, start by checking if the bulbs are burned out or if the wiring connections are loose or damaged. If the problem persists, you may need to replace the entire light or consult a professional.


Wiring your 12-volt trailer lights may seem overwhelming, but with these simple steps and tools, you can complete the task safely and efficiently. Remember to always refer to the wiring diagram and test the lights to ensure they are working correctly before hitting the road.