I tow my '13 JK all the time, and have a CooltechLLC wiring harness for my towing light solution in conjunction with a supplemental brake system, and it works great. When I was researching light solutions, I steered away from the Mopar product as I couldn't see how it wouldn't interfere with the Jeeps turn signals and still don't. Folks say it works great, so I want to know how?
Just to clarify, this harness is for towing a Jeep, not a trailer towing harness. It is used to connect a tow vehicle's lights to the Jeep to activate brake, turn, and running lamps.
As a JK sits, there is power to the brake light switch on the brake pedal under the dashboard so even if the engine is shut off, stepping on the service brake activates the brake lights. There are different designs but all supplemental brake systems operate the service brake pedal.
So... assume your pulling your Jeep down the road with your pickup and a supplemental brake system. Lets say the situation requires you to signal a turn while stopping. What mechanism keeps the Jeeps turn signals operating when the towed vehicle stops? It seems that without a switch to isolate the brake light switch or pulling a fuse to keep power from the switch, the brakes would cancel the turn signals.