Trailer wiring can be a tricky business, especially when it comes to troubleshooting. Whether you’re a seasoned pro or a newbie, wiring issues can be hard to diagnose and fix. In this article, we’ll take a look at the 5 wire trailer wiring diagram and walk you through some common issues and solutions to help you get your trailer back on the road.
What is the 5 wire trailer wiring diagram?
The 5 wire trailer wiring diagram is a standard wiring scheme used for trailers that have five wires running from the tow vehicle to the trailer. These wires include the ground wire, the brake wire, the left turn/brake wire, the right turn/brake wire, and the running lights wire.
Ground wire
The ground wire is usually white and is connected to the trailer frame. It provides a pathway for electrical current to flow back to the tow vehicle in case of a short circuit.
Brake wire
The brake wire is usually blue and is used to activate the trailer brakes when the tow vehicle’s brakes are applied. If this wire is not connected properly, the trailer brakes will not work.
Left turn/brake wire
The left turn/brake wire is usually yellow and is used to activate the left turn signal and brake lights on the trailer. If this wire is not connected properly, the left turn signal and brake lights will not work.
Right turn/brake wire
The right turn/brake wire is usually green and is used to activate the right turn signal and brake lights on the trailer. If this wire is not connected properly, the right turn signal and brake lights will not work.
Running lights wire
The running lights wire is usually brown and is used to activate the trailer’s running lights. If this wire is not connected properly, the trailer’s running lights will not work.
Common issues and solutions
Here are some common issues you may encounter when wiring your trailer and how to troubleshoot them:
Issue 1: No power to the trailer brakes
Solution:
| Possible cause | Solution |
|---|---|
| The brake wire is not connected properly | Check the connections and ensure that the wire is securely connected to both the tow vehicle and the trailer |
| The brake controller is not functioning properly | Test the brake controller by connecting it to another trailer or using a trailer with a known good brake system |
| The brake system on the trailer is faulty | Check the brake system on the trailer, including the brake shoes and drums, and replace any worn or damaged parts as needed |
Issue 2: Turn signals and brake lights not working
Solution:
| Possible cause | Solution |
|---|---|
| The turn/brake wires are not connected properly | Check the connections and ensure that the wires are securely connected to both the tow vehicle and the trailer |
| The bulbs are burnt out | Replace the bulbs with new ones |
| The fuse is blown | Check the fuse box on the tow vehicle and replace any blown fuses |
Issue 3: Running lights not working
Solution:
| Possible cause | Solution |
|---|---|
| The running lights wire is not connected properly | Check the connections and ensure that the wire is securely connected to both the tow vehicle and the trailer |
| The bulbs are burnt out | Replace the bulbs with new ones |
| The fuse is blown | Check the fuse box on the tow vehicle and replace any blown fuses |
FAQ
What is the difference between the 4 wire and 5 wire trailer wiring diagram?
The 4 wire trailer wiring diagram only includes the ground wire, left turn/brake wire, right turn/brake wire, and running lights wire. The 5 wire trailer wiring diagram includes an additional wire for the brake system.
What gauge wire should I use for my trailer?
The gauge of wire you need for your trailer depends on the size of the trailer and the electrical load it will carry. As a general rule, 14 gauge wire is suitable for trailers up to 16 feet long, while 12 gauge wire is needed for trailers up to 25 feet long. For larger trailers, you may need to use even larger gauge wire.
How do I test my trailer lights?
To test your trailer lights, you will need a multimeter or a test light. Connect the test light or multimeter to each wire on the trailer connector and have someone activate the various systems on the tow vehicle, such as the brake pedal, turn signals, and headlights. If the light or multimeter indicates that there is power to the wire, then the wiring is likely functioning properly. If not, you will need to troubleshoot the wiring to find the problem.
What is a trailer brake controller?
A trailer brake controller is an electrical device that is installed in the tow vehicle and is used to control the trailer brakes. When the driver applies the brakes in the tow vehicle, the controller sends a signal to the trailer brakes, activating them and helping to slow down the trailer.
Do I need a special connector for my trailer wiring?
It depends on the type of wiring system you have. Some trailers use a 4 pin connector, while others use a 5 or 7 pin connector. You will need to match the connector on the tow vehicle to the connector on the trailer in order to ensure that the wiring system is compatible.
With these common issues and solutions, you should be able to troubleshoot your trailer wiring and get your trailer back on the road. Remember to always check your connections and fuses and replace any worn or damaged parts as needed. Happy towing!
