Parts to Add 7-Way to Cargo Trailer With 4-Way
Updated 09/12/2025 | Published 05/27/2025
Products Featured in This Question
Question:
I have a 10 foot carry on cargo trailer with a 4 pin that i have to replace and would like to convert it to a 7 pin round connector .my truck has a 7 pin What items should I use for a nice clean set up
asked by: John M
Helpful Expert Reply:
Hey John! I recommend using the Wiring Kit for Hydrastar Electric Over Hydraulic Actuators # HS381-9000. This kit comes with everything you need for the clean setup you're looking for. You get the 7-way for the trailer, a junction box, and all of the other little parts like ring terminals to put everything together nicely. Take a look at the attached pictures.
I'm assuming you aren't adding brakes so you can cap off the unused wire on the pigtail. If you're running new wire to your lights you can pick up extra # 16-4B-1 if you need it.
If you have any other questions feel free to reply below.
(click to enlarge)
(click to enlarge)
Product Page this Question was Asked From
Wiring Kit for Hydrastar Electric Over Hydraulic Actuators
- Accessories and Parts
- Brake Actuator
- Disc Brakes
- Hydraulic Drum Brakes
- Wiring
- Hydrastar
more information >
Continue Researching
- Q&A: Adapter and Re-Wiring Kit for Lance Truck Camper with Round Pin 7-Way Plug
- Q&A: Converting 18' Flatbed Trailer From Surge Brakes To Electric Over Hydraulic Brakes
- Q&A: Will Deutsche Hydrapro CAM Adapter Module Work with DeeMax Actuator
- Q&A: Replacement for Swing Away Coupler/Actuator on MasterCraft Boat Trailer
- Q&A: 7-Way Trailer Plug Adapter or Compatibility with Lance Slide-In Truck Bed Camper
- Q&A: Marine Rated Hydrastar Disc Brake Kit for Tandem Axle 3,500 lb Axle
- Q&A: How to Replace a Lance 6-Pin Plug w/ a Standard 7-Way Connector
- Article: Trailer Wiring Diagrams
- Article: Parts Needed to Add Electric Drum Brakes to a Trailer
- Article: How to Bleed Your Trailer Surge Brakes
- Article: Breakaway Kit Installation for Single and Dual Brake Axle Trailers
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Article: Stability Control for Heavy Duty Vehicles
- Article: Best Boat Trailer Jacks
Robin H.
9/12/2025
Hey John, did the wiring kit work out for your trailer setup? I'd love to hear how it turned out because it could help others looking for a similar solution.