[Masteryota]

Zman has it right. Think of those solenoids as a big relay, except the poles are exposed. A small current circuit controls a large current circuit. This allows smaller, lighter wiring from the start switch, and keeps the heat generated from the high current away form the passenger.

Once, in my younger years, installed high powered driving lights in a vehicle I owned, and without hesitation, bypassed the relay circuit and wired straight to the switch. The second time I used them, the switch melted and shorted the wires together, creating even more problems.

Attached is a diagram for the ford solenoid, disregard the 'I' terminal, as our buggies don't use it. FWIW, you might have picked one of these up at the parts store for about the same price and not payed BMI their weird shipping rates.