The wire nutted to the red wire is the jack power and should have a 30 amp circuit breaker between the wire not and the battery.
The 2 black wires are the breakaway wires. Test the one that is wire nutted for voltage on it. If it does not have voltage on it it most likely goes to the breaks. If it has voltage the other wire, currently loose, can be connected to it to supply power to the switch.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles