I wonder where the relay is.Then the problem is likely a disconnected wire for that circuit. However, often the slide is wired direct to the battery with its own inline fuse rather than going through the mian fuse panel. Maybe the awning is Tee'd from that. You might trace the slide power circuit back from the slide controller to the battery. The slide switch is mot the main power circuit - it merely triggers the slide relay. The primary power for the slide goes to the relay, not the switch.