Myron, I don't know if these are truly helpful, as they don't specifically apply to your model year, but it may give you some leads.
dip_chassis_12v.pdf shows a panel lights connection going to the transmission interface at coordinates H-13
Schematic, Chassis Wiring.pdf shows a panel lights connection going to the transmission interface at coordinates D-4.
Adam and Sue, and a pack of little furballs
2007 Holiday Rambler Endeavor 40PDQ Limited Edition - Cummins ISL 400
2013 Ford F-150 FX4 toad - USGear Unified Tow Brake, Roadmaster Blackhawk II Tow bar, Blue Ox baseplate
Home base near Buffalo NY, often on the road to a dog show