Geof: When I got my first 89 Royale Prevost I experianced the same thing. We found the 24V to 12V relays hidden in the driver side rear closet below and to the right of it. It takes a midget to even get close enough to see them. As it turned out they were wired wrong and had to be re-wired to make the female plug at the bumper work with the coach lights. After you get that plug working your next task is to mate it to your jeep lights. There is a couple of ways to accomplish this. Camping world has setups to do it a couple of ways. I found the easiest way was to run trailer light wires from the male connector to the back of my envoy and drill the tail light housings and install bulb sockets on each side. Install two element bulbs in the sockets and you have tail, turn and stop lights without interfering with you tow vehicle light system. First open you tail light lens to make sure your housings have room for the extra bulb. Try to get the aid of someone with electrical experiance to help you if you can. Good Luck
Harry
Shirley & Harry / 2000 Liberty / 2008 GMC Envoy Denali