How to Wire a 4 Pin Trailer Connector to a 7 Pin Connector?

May 09, 2021 2 min read

With new advancements and technology, there is a lot of competition in the world of solder connectors. There are numerous connectors, and each comes with unique features. But, when it comes to connectors and adapters of heavy machinery, there is a good variety.

From 4 to 7 pins; and adapters with extra wires; you will get everything. There are a lot of adapters that connect to hard wires and then to the trailer. However, there is always a risk of blown-fuse and wiring issues. Keep on reading about how to wire a 4 pin trailer connector to a 7 pin connector. 

What is a pin trailer connector?

To safely connect the turn signals, brake lights, and electrical wiring; a trailer requires a trailer connector to protect the wires. The trailer adapter converts a tow vehicle and other wiring connections to a 7 pole wiring connector for trailers with hydraulic brakes. 

What is a 7 pin connector?

A 7 pin connector is more efficient and has more than three functions. As compared to a 4 pin connector; a 7 pin connector can also run the trailer's 12-volt system, reverse lights, and electric brakes. 

Not to mention, the 7-pin connector can also handle running lights, left and right turn signals, and brake lights. 

How to wire a 4 pin trailer connector to a 7 pin connector?

Making a connection of a 4 pin trailer connector to a 7 pin connector is not difficult. However, you may have some experience in electrical power connections; as it’s a bit tricky.

Step 1: 

Cut the connection of the 4-pin connector off the harness. There are color codes at each tail light; note the harness color codes. Both the taillights must have a common color. 

However, the left and right turn signal lights have different colors. There are a total of three colors in the wiring harness. 

Step 2: 

Do a test light with the 7-pin connector. Turn on the vehicle tail lights and note the location of the pin. 

Now, do the same with both left and right turn signals. Observe the location of the ground wire and follow the wire to the body of the ground. 

Step 3: 

Crimp the connector and then plug the connector into the towing vehicle. Test run each circuit for any errors.

Step 4: 

With the help of electrical tape, wrap the exposed wires and make a wiring harness. Make sure that there are no spliced wires; as they can lead to electrical damages. 

Making a connection of a 4 pin connector to a 7 pin connector or a trailer system is not difficult. However, it demands patience and concentration. We would recommend you to take some expert advice if you know nothing about connectors and trailer systems.