I found this wire just chilling on the passenger side. It has a long black plastic cap on the end of it. I just tucked it back in the side panel, but anyone know what it is?
GregjOk. I think I found it. On the passenger side footwell, behind the plastic, near where the door’s connector is, lives the BCM. On a tow-package factory equipped JL the provided harness taps the signal from the The Dark green with a white stripe wire going to pin 18 of the BCM.
I used this post as a reference; https://www.jlwranglerforums.com/forum/threads/jeep-jl-wrangler-wiring-diagrams.19185/
He says he doesn’t have aux switches(HD electrical), for 2018 JL trailer tow and HD electrical is one package..I believe that is just the wire that comes out of the BCM that would go to the Trailer Tow Package, @Markham doesn't say if he has Trailer Tow or not but if you look at the wiring diagram it does show a dark green/white wire coming out of the BCM to the Aftermarket Electric Brake Module.