I don't have any lights on the trunk, I went with the quick-release rack and didn't want to bother with detachable light connections. I stopped at the HD dealer this morning and asked the service tech to show me the wiring schematic for the rear light display unit. It was the red/yellow wire. I hooked it up under the seat when I got home, took me about 15 minutes. Works fine and will take it out tonight after dark. Thanks for your help.
Stay safe, but ride.