Gary,
Diagrams for the 2000 and 2002 Marquis are available in our Library an are probably identical to your 2001. Select the Private Members Only board, then Link to Coach Assist, then the hyperlink. Page down to the Marquis Wiring diagrams. The one for the 2002 Marquis is what I would start with. If it is different from the one in your coach, check the 2000 Marquis diagrams just above the 2002 listing.
Steve