[BB_TX]

Under that slide there should be an electrical umbilical cord or wire bundle that extends with the slide. My first thought is that there is a junction box under your main floor where those wires connect to the main trailer wiring. And that the slide moving in and out and moving that wire bundle are causing wires in that J box to move. Loose wires could be alternately touching and separating in turn making and breaking a circuit. A poor wire nut connection could be a culprit. A wire broken inside its insulation can do the same.