A 7 way wiring harness is a necessary component for towing trailers and vehicles. It connects the electrical systems of the trailer and tow vehicle in a safe and effective manner. Knowing how to properly wire a 7 way harness is crucial for the safety of yourself and other drivers on the road. This article will provide a detailed guide on how to wire a 7 way harness.
What is a 7 Way Wiring Harness?
A 7 way wiring harness is a set of wires that connects the electrical systems of a towing vehicle and a trailer. It consists of seven wires that provide power and signal to various trailer lights and brakes. The seven wires are color-coded to ensure proper connection and avoid confusion.
The seven wires in a 7 way wiring harness are as follows:
| Wire | Color | Function |
|---|---|---|
| 1 | Black | Battery Charge |
| 2 | Brown | Tail/Running Lights |
| 3 | Green | Right Turn/Brake Lights |
| 4 | Yellow | Left Turn/Brake Lights |
| 5 | Blue | Electric Brakes |
| 6 | White | Ground |
| 7 | Red | Auxiliary/Reverse |
1. Battery Charge Wire (Black)
The battery charge wire provides power to the trailer’s battery to keep it charged while driving. This wire is typically not used for smaller trailers, but is required for larger trailers or RVs with onboard batteries.
2. Tail/Running Lights Wire (Brown)
The tail/running lights wire provides power to the trailer’s tail lights and running lights. These lights are required by law to be on while driving at night.
3. Right Turn/Brake Lights Wire (Green)
The right turn/brake lights wire provides power to the trailer’s right turn signal and brake lights. When the tow vehicle’s right turn signal is activated, the trailer’s right turn signal and brake lights will also activate.
4. Left Turn/Brake Lights Wire (Yellow)
The left turn/brake lights wire provides power to the trailer’s left turn signal and brake lights. When the tow vehicle’s left turn signal is activated, the trailer’s left turn signal and brake lights will also activate.
5. Electric Brakes Wire (Blue)
The electric brakes wire provides power to the trailer’s electric brakes. When the tow vehicle’s brakes are applied, the trailer’s brakes will also be applied. This wire is only necessary if the trailer has electric brakes.
6. Ground Wire (White)
The ground wire provides a ground connection for the trailer’s electrical system. It is important for the proper function of the trailer’s lights and brakes.
7. Auxiliary/Reverse Wire (Red)
The auxiliary/reverse wire is used for various purposes such as charging the trailer’s battery or activating the trailer’s reverse lights. This wire is not always used, but is helpful for certain trailer setups.
How to Wire a 7 Way Harness
Step 1: Gather Materials
Before beginning, make sure you have all necessary materials. You will need a 7 way connector, a wire stripper/cutter, electrical tape or heat shrink tubing, and a wiring diagram for your specific towing vehicle and trailer.
Step 2: Strip Wires
Using the wire stripper/cutter, strip approximately 1/2 inch of insulation off the end of each wire on both the tow vehicle and trailer.
Step 3: Connect Wires to Connector
Refer to the wiring diagram for your specific towing vehicle and trailer to properly connect each wire to the 7 way connector. Use electrical tape or heat shrink tubing to secure the connections and prevent any exposed wires.
Step 4: Test Connections
After all wires are connected, test each function of the trailer (tail lights, turn signals, brake lights, electric brakes) to ensure proper connection and function.
FAQs
What if my towing vehicle or trailer has a different wiring setup?
If your towing vehicle or trailer has a different wiring setup, refer to the wiring diagram for that specific setup. It is important to follow the diagram to avoid any electrical issues or safety hazards.
What if I am unsure of how to properly wire a 7 way harness?
If you are unsure of how to properly wire a 7 way harness, seek the assistance of a professional mechanic or electrician. Proper wiring is crucial for the safety of yourself and other drivers on the road.
Can I use a 7 way harness for a small trailer?
Yes, a 7 way harness can be used for a small trailer, but may not require all seven wires. Refer to the wiring diagram for your specific trailer to determine which wires are necessary.
Do I need a battery charge wire for my trailer?
If your trailer has an onboard battery, a battery charge wire is necessary to keep the battery charged while driving. If your trailer does not have an onboard battery, a battery charge wire is not necessary.
What is the difference between a 4 way and 7 way wiring harness?
A 4 way wiring harness provides power to only the trailer’s tail lights, turn signals, and brake lights. A 7 way wiring harness provides power to all necessary trailer lights and electric brakes.
What if I am having issues with my trailer’s electrical system?
If you are having issues with your trailer’s electrical system, first check all connections and fuses. If the issue persists, seek the assistance of a professional mechanic or electrician.
A 7 way wiring harness is an important component for towing trailers and vehicles. Proper wiring is crucial for the safety of yourself and other drivers on the road. Follow the steps and guidelines in this article to properly wire a 7 way harness.
