On my 2005 Excursion, the slide relays/controllers are in the electrical bay. I had a problem with my passenger side bedroom slide not working, so I swapped relay/controllers and it worked. Turned out, the connector to the controller was loose in the socket! All is well now.
2005 Fleetwood Excursion 39L, 350 Cat, Allison 3000, 2007 Honda CRX Toad