With all the different shapes and sizes of connectors found on vehicles, trailers, campers, and boats, finding the right trailer wiring for your application can be challenging. Understanding the different functions and configurations of each connector type is essential for ensuring a proper electrical connection between your towing vehicle and trailer.
The 4-way flat is the most common connector found on small utility trailers and campers that don't require brakes. You'll also find these on basic towed vehicle wiring kits. This connector provides the three essential lighting functions: running lights, turn signals, and brake lights, plus ground wiring.
The 4-way round is an excellent alternative to the 4-way flat as it provides a more secure connection with its receptacle lid and plug tab design. Important noteMake sure you're buying the correct amperage version for your needs: There are two versions available – a standard 20 amp version with four equal-sized pins and a heavy-duty 35 amp version with a larger ground pin. These are not compatible with each other. All 4-pin coiled cables are the standard 20 amp version.
The 5-way flat connector is commonly found on utility trailers and campers that require electric brakes. This connector includes all the functions of the 4-way flat plus an additional pin for electric brake connection. Note that this style is generally considered a temporary setup due to its susceptibility to disconnection and corrosion over time.
The 5-pin round connector has become very popular with RV owners who tow a vehicle behind their motorhome. The fifth pin provides support for a coach signal line from the braking system in the towed vehicle. It's also used for trailers with surge brakes, where the additional wire connects to backup lights to disengage the trailer's brakes when reversing.
The 6-way round connector builds on the 4-way and 5-way designs with two additional pins for expanded functionality. Most commonly, these extra pins are used for a 12-volt "hot" lead and electric brakes. This configuration is popular for horse trailers where the 12v power illuminates the interior of the trailer. It's also frequently used for towed vehicles to provide charging power from the motorhome to the vehicle's battery, which may be used by an auxiliary braking system.
The 6-way square connector can be challenging to work with as adapters and replacement parts aren't always readily available. However, we carry a complete line of 6-way square to standard 7-way wired assemblies for specific trailer manufacturers, making your connection problems a thing of the past.
Note: Color codes can vary between different trailer manufacturers.
The 7-way connector is the most popular connection type found on late model SUVs, trucks, and RVs. It includes all features of the other connectors plus a pin for backup lights. There are two variants – one with flat pins (blades) and one with round pins. The flat pin version is far more common and is typically factory-installed on newer vehicles with trailer hitches.
Coiled electrical cables are the perfect solution for any towing setup. These replace straight cables or loose wire configurations that tend to drag and get damaged between the vehicle and trailer. With these "plug and tow" coiled cords, you'll have reliable lighting and electric brake connections that stay off the ground.
Our high-quality coiled cables feature molded connectors on each end for strong, reliable connections. They're available in 4, 5, 6, and 7-way configurations, with both flat and round versions depending on your specific needs.
These specialized adapters are designed to work with specific vehicle manufacturers or trailer brands. They ensure perfect compatibility between your tow vehicle's factory wiring and various trailer configurations.
The connector type you need depends on your trailer and tow vehicle. Check your trailer first to identify what connector it has, then match it to your vehicle's connector or use an adapter. If installing new wiring, consider the functions needed (lights, brakes, power) and select a connector with enough pins for all functions.
Yes, you can upgrade from a 4-way to a 7-way connector. You'll need a wiring harness adapter that adds the additional pins for functions like electric brakes, 12V power, and backup lights. However, you'll need to run additional wiring for these functions if they weren't previously installed.
Corrosion is primarily caused by moisture, road salt, and environmental contaminants. When moisture gets trapped in the connector, it creates a perfect environment for corrosion, especially when combined with road salt or other chemicals. Regular cleaning and applying dielectric grease can significantly reduce corrosion.
There's no set timeframe for replacement, but you should inspect your connector regularly for signs of damage, excessive corrosion, or loose connections. If you notice intermittent lighting issues, pins that feel loose, or excessive corrosion that can't be cleaned, it's time to replace the connector.
The 7-way flat pin (blade) connector is more common on newer vehicles and has rectangular-shaped pins arranged in a specific pattern. The 7-way round pin connector has round pins and is less common. These are not interchangeable without an adapter, so make sure you know which type you have before purchasing accessories.
Our expert team is ready to assist you in selecting the perfect trailer wiring solution for your specific needs.
This guide should help you determine the right connector type for your trailering needs. Browse our complete selection of connectors, adapters, and vehicle-specific wiring kits in our trailer wiring category and contact us if you need any assistance with your selection.