Update!!
I really didn't want to open up the rear hatch on my brand new Cherokee, but I had to finish this. I started prying the inside panel loose, and lo and behold a small panel pops loose and there is the back of the left tail light. I look and there is another panel behind the other light. I then slap my forehead and utter DUH.
The wire color is white with a light green trace. I cut it, inserted the diode and I am done with it.
Thanks for the feedback. I think we will start seeing a lot of these new Cherokees behind motor homes in the future.
We love it so far with only 650 miles on it and a trip coming up next month.
Dave