The 815 has an option for pods which are used to make it a short bed camper. The pod provides storage, but more importantly parking and brake lights. There is usually a glued in 4 prong flat plug at the corner.
Right side would have brown (parking), green (turn/brake) and white (ground). Left side has brown, yellow, and white. Believe the wires are visible in the small compartment just inside the door.
2015 Ram 3500 4x4 Crew Cab SRW 6.4 Hemi LB 3.73 (12.4 hand calc avg mpg after 92,000 miles with camper)
2004 Lance 815 (prev: 2004 FW 35'; 1994 TT 30'; Tents)