Re-Wiring Old Travel Trailer to Convert from 5-Pole Flat to 7-Way RV Style Blade Connector
Question:
Hi there, I have an old travel trailer which I am rewiring and I have a question. The trailer has a 5-flat wiring harness on it, which is what I need, but I need a longer lead/plug to connect to the towing vehicle. The towing vehicle has a 7-blade plug. I am wondering if it would cause any issues to wire a 7-Way Molded Trailer Wire Connector 8foot Long code H20046 to my five flat wiring harness using a junction box by essentially omitting the unneeded wires on the 7-blade connector? As long as the wires are connected to the correct corresponding wires, can I expect any dysfunctions by doing this? Thank you!
asked by: Lulu
Helpful Expert Reply:
When a tow vehicle and trailer have different style connectors the options are to re-wire one of them or to use an adapter. Adapters are fine for a quick fix but for long-term reliability you are better off doing exactly as you suggest - wiring in a new connector on the trailer to match the tow vehicle. This avoids the adapter and the potential for trouble down the road from the extra connection points.
A junction box like # 38656 is a perfect way to connect the 7-way harness # H20046 from Hopkins to your trailer's existing wiring. The linked video illustrates.
You will also need ring terminals to make the connections inside the box; you will need enough for all of the wires on both sides of the box. I suggest 3M ring terminals # 44-5310A which work with 10- to 12-gauge wires. You'll need a crimping tool to affix the ring terminals to your wire leads. You may prefer to order a re-wiring kit, part # HM51020 from Hopkins, since it includes the crimping tool and various other wiring components in a handy case. Note you'll still need to order some additional ring terminals as the kit includes only 2.
Take care to match the wires in the junction box by FUNCTION not by color. Trailers often use specific colors for specific functions but there is no guarantee that your trailer is wired in the conventional manner. So it is BEST to TEST. You can apply 12V power directly to each circuit on the trailer connector to confirm what that wire does. Once you know that you can match the wires up by function to those on the Hopkins molded connector # H20046.
There is a legend on the product page that tells you what each wire in the Hopkins connector does so you will know how to match your functions for both halves of the wiring joined in the box.
Products Referenced in This Question
Ring Terminal - 12-10 Gauge Wire - 3/16" Ring ID
- Wiring
- Wire Connectors
- Ring Terminals
- 3/16 Inch Diameter
- 12-10 Gauge
- Flint Hill Goods
more information >
Hopkins Deluxe Trailer Wiring Installation Kit
- Wiring
- Tools for Wiring
- Wiring Kits
- Installation Kit
- Hopkins
more information >
Product Page this Question was Asked From
Hopkins 7-Way RV Style Connector with Molded Cable - Trailer End - 8' Long - RV Standard
- Trailer Wiring
- Trailer Connectors
- Trailer End Connector
- 6 - 10 Feet Long
- Plug and Lead
- 7 Round - Blade
- Hopkins
more information >
Featured Help Information
Instructions
Miscellaneous Media
Continue Researching
- Q&A: How to Tell If MORryde Rubber Equalizers Will Fit Trailer
- Article: Trailer Wiring Diagrams
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Article: How to Install E-Track in 3 Easy Steps
- Article: How to Choose the Right Trailer Hitch Class
- Q&A: Brake Controller Installation on 2016 Mercedes-Benz Sprinter
- Q&A: Replacement Kwikee Electric Steps for a 2005 Jayco Greyhawk 31SS
- Q&A: Is Bow in 3,500 lb Trailer Axle Enough Camber for Loaded and Unloaded Trailers
- Q&A: Correct Replacement for AL-KO 7230 Hub/Drum and Brakes
- Q&A: Recommended Square Bulldog Jack with 5,000 lb Capacity
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Article: 7 Common Questions Everyone Has About Trailer Tires
- Q&A: Replacement RV ladder for 2007 Monaco Diplomat
- Article: Calculating Portable Generator Power Needs