Choosing the right connectors for your trailer wiring

With all the different shapes and sizes of connectors it's not always easy when it comes to trailer wiring and choosing the right one for your application. Trailer or towed vehicle wiring can be confusing with all of the different purposes for connectors that you might not be aware of. You need to make sure that you choose a connector with the appropriate number of pins for the required functions of your trailer or towed vehicle. If you have a connector that is located under the vehicle you might want to connect it to the vehicle by using a mounting bracket to help prevent damage from a angling wire. It is important to know what type of connector you need and we are here to help.

4 Way Flat Trailer Connectors

4 way flat

You will find this style connector on small utility trailers and campers that do not require brakes as well as basic towed vehicle wiring kits. This type of connector allows for the basic connection of the three lighting functions which include running, turn, and brake lights. It also comes with one pin for ground wiring.

Wiring code:
  • White = Ground
  • Brown = Running Lights
  • Yellow = Left Turn Signal & Brakes
  • Green = Right Turn Signal & Brakes

4 Way Round Trailer Connectors

This is a great replacement for the 4 way flat connector since it provides a secure connection between the receptacle lid and plug tab. Be careful with the 4 way connector, there is a version considered heavy duty with a 35 amp rating that feature a larger ground pin. This will not mate with the standard 20 amp version that has 4 pins of the same size. If your looking at the 4 pin coiled cables they will all be the standard 20 amp version. This type of connector allows for the basic connection of the three lighting functions which include running, turn, and brake lights. It also comes with one pin for ground wiring.

Wiring code:
  • White = Ground
  • Brown = Running & Brake Lights
  • Yellow = Left Turn Signal
  • Green = Right Turn Signal

5 Way Flat Trailer Connectors

You will find this style connector on utility trailers and campers that require brakes and is generally considered a temporary setup due to it's ability to become easily disconnected or corroded. This type of connector allows for the basic connection of the three lighting functions which include running, turn, and brake lights along with a ground pin and electric brake connection.

Wiring code:
  • White = Ground
  • Brown = Running Lights
  • Yellow = Left Turn Signal & Brakes
  • Green = Right Turn Signal & Brakes
  • Blue = Electric Brakes

5 Way Round Trailer Connectors

The 5 pin round connector allows for the basic functions, as well as a pin to provide support for another function. This connector has become very popular with RV'ers who tow a vehicle behind their motorhome and want to add a coach signal line from the braking system in the towed vehicle. This may also be used for trailers with surge brakes. The additional wire is tapped into the backup lights to disengage the trailer's brakes when the vehicle is reversing.

Wiring code:
  • White = Ground
  • Brown = Running Lights
  • Yellow = Left Turn Signal & Brakes
  • Green = Right Turn Signal & Brakes
  • Blue = Electric Brakes

6 Way Round Trailer Connectors

Like the 4 and 5-way connectors, the 6-way connectors also allows for the three basic lighting connections and comes with the ground pin and two additional pins to provide two extra functions. The two extra pins are commonly used for 12 volt "hot" lead and electric brakes. The round connectors are typically used for horse trailers which use the the 12v power to light up the inside of the trailer. This configuration is also popular for towed vehicles to provide power for a charging line from the motorhome to the vehicles battery which is being used by a braking system.

Wiring code:
  • White = Ground
  • Brown = Running Lights
  • Yellow = Left Turn Signal & Brakes
  • Green = Right Turn Signal & Brakes
  • Blue = Electric Brakes
  • Black = 12v Power

6 Way Square Trailer Connectors

If you've come across this style connector on your trailer, more than likely you had to be asking yourself "WHY!" Mainly because it will be nearly impossibly to easily find an adapter to hook this style connector to your tow vehicle. And finding replacement connections can be just as frustrating. But your in luck since you found us, we carry a complete line of 6 way square to standard 7 way wired assemblies for your specific trailer manufacturer. Click here to check out RV Pigtails trailer wiring products.

Wiring code:
  • White = Ground
  • Brown = Running Lights
  • Yellow = Left Turn Signal & Brakes
  • Green = Right Turn Signal & Brakes
  • Blue = Electric Brakes
  • Black = 12v Power
Note: color codes can vary between different trailer manufacturers.

7 Way Trailer Connectors

The 7-way connector is the most popular trailer connection type found on late model SUV's, trucks and RV's and comes with everything the others come with along with the availability for backup lights. There are two different types of 7-way connectors, one with flat pins (blades) and one with round pins. The round pin connectors are very uncommon, while flat pins are common and often found on newer SUVs and trucks that come from the factory rigged with a trailer hitch.

Wiring code:
  • White = Ground
  • Brown = Running Lights
  • Yellow = Left Turn Signal & Brakes
  • Green = Right Turn Signal & Brakes
  • Blue = Electric Brakes
  • Black = 12v Power
  • Orange or Red = Auxiliary / Backup Lights

Coiled Cables

Coiled Electrical Cables are the perfect solution for anyone who tows a trailer or towed vehicle. Coiled Cables replace those straight cables or loose wire setups that hang down and drag between the vehicle and trailer. It's not long before you no longer have lights on that trailer and even worse non working electric brakes! These “plug and tow” coiled cords are available with high quality molded connectors on each end providing for a strong & reliable connection. Available in 4, 5, 6 & 7 way some in flat and all in round versions along various combinations.

Click Here to view our selection of Coiled Electrical Cables


This should be a helpful guide to help you figure out what type of connector fits your trailering needs. You can find all your connector needs for your RV and trailer wiring under our trailer wiring category so make sure you browse through all our products and contact us if you need any assistance in your selection.

The Right Connectors For Your Trailer or Towed Vehicle