How To Upgrade 4-Flat Trailer Connector To Work With Electric Brakes
Updated 09/02/2025 | Published 06/27/2025
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Question:
I installed the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector with my receiver and I am wondering what you suggest if I want to upgrade my connection to accommodate a trailer with brakes.
asked by: Josh
Expert Reply:
Hey Josh, thanks for reaching out. We actually custom make our own wiring kit specifically for this purpose. What you will need is the following:
- Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires # ETBC7
This kit is made specifically to be used on vehicles with an existing 4-flat trailer connecter. It contains everything needed to upgrade the 4-flat to a 7-way which is what you need for a trailer with brakes. It also contains the necessary wires for a brake controller, which will be required.
For the brake controller I recommend the Redarc Tow Pro Liberty # RED52VR. It installs behind the dash, and all you see is the small LED control knob. It will install using the included universal pigtail.
I have included links to a few of our install videos, as well as a few pictures you should find helpful.
What kind of trailer will you be pulling? Just curious because it looks like you might have a ProMaster van and sometimes those setups are pretty cool
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Product Page this Question was Asked From
Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires
- Accessories and Parts
- Trailer Brake Controller
- Installation Kits
- etrailer
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on Accessories and Parts
Jesse M.
9/2/2025
Hey Josh, did you get a chance to install the Universal Installation Kit and the Redarc Tow Pro Liberty brake controller? How did it work out with your trailer setup? I'm asking because your experience could really help others looking to upgrade their trailer connections.