Follow the big wire from the chassis battery positive terminal. There are probably 2 wires, one to the starter, and one to the disconnect. Once you find the disconnect, the 2 small terminals power it. Put 12 volts on one terminal momentarily, the relay pulls in or drops out, put 12 volts to the other small terminal, it goes the other way. You can use a length of wire directly from your battery to test it.
As far as where this power comes from, most likely a fuse box, mine has 3 amp fuse. in a fuse box under the hood.
06 Hurricane 34FT WH W20 Chassis 8.1L 120K, Steersafe, Koni Shocks, DIY Trac Bar, Tri-Metric 2025RV Battery Monitor, 4-6V Batteries, Scan Gauge 2, Crossfires, 735W Solar Morningstar MPPT-60, KVH R5 In-Motion Sat, XM Radio, 07 Chevy Malibu Maxx Toad, Falcon 2, Brake Buddy, Escapee