Yunnergo Flat Trailer Harness Plug Kit for Silverado 2001–2019 — Pre-wired 7‑way & 4‑way with Mounting Bracket

Yunnergo's Flat Trailer Harness Plug Kit (Part 55774) is a pre-wired 7-way and 4-way connector set with mounting bracket and hardware designed to restore trailer lighting and towing connections on compatible GM trucks and vans.

This wiring kit supplies both a 7-way multi-tow connector and a 4-way flat plug in one package, assembled to reduce installation time and avoid cutting into factory wiring. Built with reinforced ABS housings and a protective outer layer, the harness is made for everyday towing use. It fits a range of Chevrolet and GMC vehicles from the early 2000s through 2019 — check the vehicle list below before purchasing to ensure fitment.

Which vehicles does this plug kit fit?

The kit is intended for specific Chevrolet and GMC models across several model years. It covers many Silverado, Avalanche, Express, Suburban and Colorado variants listed by year and trim; compatibility depends on the factory socket and bumper location. Always compare the part picture and vehicle year to avoid ordering the wrong item.

• Silverado 1500/2500/3500/2500HD: 2001–2019
• Avalanche 1500: 2002–2006
• Express 2500: 2008–2017
• Suburban 1500: 2000–2014
• Colorado: 2008–2019

How easy is the installation and what’s included?

Installation is straightforward because the harness arrives pre-assembled and plugs into the vehicle's existing socket without splicing. The package contains the 7-way connector, the 4-way flat plug, a mounting bracket and the necessary screws and nuts, plus written installation guidance. No advanced wiring skills are required for owners comfortable using basic hand tools.

• Pre-assembled wiring harnesses (7-way and 4-way)
• Mounting bracket shaped for bumper or receiver mount
• Installation accessories: screws and nuts included
• Installation instructions provided for reference

What are the construction and durability features?

The connectors use high-strength ABS plastic housings with an external protective layer to guard wiring against abrasion and road grime. Contacts are arranged to keep reliable signal and power transfer to trailer lights and brakes. While not sealed for submersion, the design is built to withstand normal road exposure and towing conditions.

• ABS plastic connector bodies for impact resistance
• Outer protective layer over the wiring bundle
• Pre-assembled joints reduce failure points from field splicing
• Designed for standard towing electrical loads

Can this kit support different trailer setups?

Yes — both 7-way and 4-way plugs are included so you can connect trailers with basic lighting or full multi-function setups that require power for brakes and auxiliary circuits. Switching between plugs is quick and keeps you prepared whether you haul a small utility trailer or a heavier load with electric brakes. For larger electrical demands, verify your vehicle’s towing capacity and circuit ratings.

• 4-way flat for tail, turn and brake lights
• 7-way round for electric brakes, auxiliary power and reverse feed
• Use included bracket to position connectors for easy access
• Ideal for mixed trailer fleets or future upgrades

Who is this for: This Yunnergo harness kit suits owners of compatible Chevy or GMC trucks and vans who need a fast, factory-style replacement for trailer connectors. It’s a good option for DIY installers, fleet maintenance techs, and anyone who wants both 4-way and 7-way connections ready to use without splicing or complex wiring. Confirm your vehicle year and bumper socket type before ordering to ensure correct fitment.