That's great now I have some things to look at. So I should be able to take a wire from the ground side of the lights to the chassis and see if that fixes it, then I'll know I have a loose ground wire to find.
So both batteries and all wiring systems should all be going to the same chassis ground, is this correct?
Thanks so much for the help everyone. I'm taking it for a weekend getaway tomorrow. I'll just not use the interior lights this weekend and try to troubleshoot it next week. I appreciate the help!
Arnie