Marlau - I looked at an exterior picture of your floorplan and it looks like you have the electric "cable" (Norco/BAL) slide system in the bedroom.
I believe you may have to start the process of removing a section of the mattress platform (a few screws in the plywood up top at the head). Once that's open, you "may" be able to see the wiring the comes up from the floor area and make the connection to the motor.
"IF" the power feed for the slide motor comes up through the floor under the bed, it's possible that you'll need to remove the paneling on the floor of the storage under the bed. Once removed, you may find that a wire nut is loose or fell off the DC connection from the coach wiring to the motor wiring.