Oyviny USCAR 7‑Pin to 4‑Pin Trailer Wiring Harness — 41in 16AWG Pure Copper Adapter for LED Tailgate Light Bars

The Oyviny Plug & Play USCAR 7-pin to 4-pin wiring harness converts a factory USCAR 7-way socket into a standard 4-way flat connector for powering LED tailgate light bars and basic trailer lights.

This compact adapter lets you tap the existing OEM USCAR 7-pin trailer tow plug on trucks and pickups to feed a 4-pin flat trailer plug without cutting or splicing vehicle wiring. Built with 16 AWG pure copper conductors and a protective slit loom, the harness maintains the factory 7-way connection while exposing Brake, Turn, and Tail signals to an added 4-pin output. It’s a straightforward option when you need a simple, temporary or semi-permanent wiring solution for under-tailgate light strips, small trailers, or auxiliary lighting.

How does this harness power an LED tailgate light bar?

The adapter routes the vehicle’s brake, turn, and tail lamp circuits from the USCAR 7-way socket into a standard 4-pin flat plug, so a light bar can use those signals without modifying the factory loom. Installation plugs directly into the OEM USCAR port and provides a 4-way receptacle for the accessory.

• Plugs into factory USCAR 7-pin socket — no wire cutting.
• 4-pin flat output supplies Brake, Turn, and Tail circuits.
• 16 AWG pure copper conductors for reliable conductivity.
• 41-inch cable length with slit loom for routing flexibility.

Will this affect vehicle safety systems like parking assist or trailer detection?

Some trucks with rear parking sensors, trailer detection or blind spot systems may interpret a connected light bar or 4-pin load as a trailer. That detection can change or disable certain driver-assist features when the adapter and accessory are attached.

• Vehicles with factory trailer detection may alter sensor behavior when a 4-pin load is present.
• Backup assist or blind spot alerts can be disabled by the vehicle while a trailer load is sensed.
• Recommended: confirm compatibility with your truck’s tow package functions before permanent installation.

Which vehicles and towing setups is this adapter compatible with?

The harness is designed for trucks and SUVs equipped with a factory USCAR 7-pin towing socket. It’s common on many modern pickups and can accommodate aftermarket light bars or standard 4-pin trailer wiring requirements.

• Intended for vehicles with USCAR 7-way factory tow package only.
• Works with many GMC, Ford, Dodge Ram, Toyota Tacoma/Tundra, Jeep and similar models when factory plug is present.
• Useful for light bars, small trailers and trailer-style accessories needing a 4-flat connection.

What are the build details and installation notes?

The adapter uses durable black plastic connectors and a protective black slit loom over 16 AWG pure copper wire. The 41-inch harness length gives enough reach to mount a 4-flat receptacle under the tailgate or at the bumper for easy hookup.

• 16 AWG pure copper conductors for stable electrical flow.
• Black slit loom for abrasion resistance and neat routing.
• Plug-and-play mating: installs without cutting factory wiring.
• Keep in mind vehicle-specific features that may be affected by an added load.

Who is this for? The Oyviny USCAR 7-pin to 4-pin adapter suits truck and SUV owners who already have a factory USCAR 7-way tow socket and need a clean, reversible way to power a 4-flat accessory — commonly LED tailgate light bars, small trailers, or occasional towing where a full rewire isn’t desired. It’s best for DIYers and installers looking for a non-invasive, durable wiring solution; verify your vehicle’s tow package and driver-assist behavior before use.