What Trailer Wiring Do I Need on My 2021 Jeep Grand Cherokee (Without Factory Tow Package)?  

Expert Reply:

For setting up your 2021 Jeep Grand Cherokee (without factory tow package) for wiring, you will first need a 4-way harness. For a 4-way that is compatible with your vehicle, I recommend the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C62VR. The Curt connector will allow you to install a 7-way into your vehicle for the functions you need for towing if you need those functions.

For a 7-way, once you have the 4-way installed, you need the Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat # ETBC7. This will give you the ability to hook up all of your trailer's tail light functions as well as add a brake controller. If you need help with installing the # ETBC7 with the for your vehicle's brake controller, I went ahead and attached the wiring diagram to this answer.

As far as a brake controller, I recommend the Curt TriFlex Trailer Brake Controller # C51140 with the Universal Wiring Adapter for Curt Controllers # C51515. The TriFlex will give you proportional brake control which means the controller will activate in proportion to your vehicle's braking action. It also comes with continuous diagnostic checks.

If you want a fancier wireless option, I recommend the Curt Echo # C51180. Like the TriFlex, the Echo also includes a proportional braking system. What sets the Echo apart from the competition is the ease of installation. You will be able to avoid complicated wiring and bulky control units in your vehicle.

I went ahead and attached videos of the installation process of the TriFlex and the Echo to this answer.

# ETBC7 Wiring Diagram with Brake Controller
(click to enlarge)