The 3 amp fuse for your factory solar panel is in the battery control center. Black metal box built by RV Custom Products. Should be under the hood on your vintage. Wiring print is on the back side of the cover. The LED lamp indicator, for the OEM solar, inside your coach, is subject to fail. It is combined with 3 diodes to make it glow. Wiring print available if needed.
The factory wires are just barely large enough for the factory 5 watt panel.
Do NOT use the already installed wires. They are to small.
Consider running the new larger wires down the refrigerator vent.
Richard