Trailer Wiring Diagrams | etrailer Sometimes the vehicle manufacturer will run the wires to an easily accessible plug underneath the vehicle or behind the paneling in the back cargo area. T-Ones come pre-wired with a 4-way flat trailer connection and can be expanded to 5-way, 6-way, or 7-way trailer connections through the use of a wiring adapter. Custom Hardwire Kit4-Way Flat Trailer Connector · 4-Way Flat Vehicle Connector Videos of 7 way trailer plug wire colors Click to view on YouTube5:24Wiring a 7 Way Trailer Plug60 viewsYouTube · 9/17/2018Click to view on YouTube7:53etrailer 7 Way Trailer Wiring Upgrade Kit Installation - etrailer79K viewsYouTube · 5/11/2016Click to view on YouTube3:24how to wire a 7 way trailer plug. the RIGHT way..295K viewsYouTube · See more videos of 7 way trailer plug wire colors Trailer Wiring Codes For 4 Pin To 7 Pin Connector - YouTube Click to view on Bing1:25Jun 14, 2015Trailer Wiring Codes For 4 Pin To 7 Pin Connector How to Test and Wire Trailer Lights Using a Hopkins 6:05. Mark Jenkins 178,593 views. 6:05. How To Test 7 Way Trailer RV electrical PlugAuthor: Thinking out side boxViews: 80K 7-way - 7 pole RV Travel Trailer Connector Wiring Color Code Pictured below is the RV 7-way flat-pin umbilical connector, also called the 7 pole plug, which is the connector style most commonly used on RV travel trailers and fifth wheels This connector is made by many companies but they are supposed to be interchangeable and the wiring color code is observed among the various brands.