Hi Erick
On the wiring diagram it is called "Current Limit Relay" how it functions is that if the current flow exceeds a limit it starts opening and closing very fast to limit the current flow.
The Overload Protection used on CMPs are varied but in general, they can not be called circuit breakers or fuses. They are a current regulator and they either work or they don’t. If you over load (short) the system the unit sit there and vibrate limiting the current flow to 25-30 amps hopefully low enough that a fire doesn’t start. The one on my HUP functions great. Before I put in the new wiring harness the old one shorted out and you could hear the limiter buz like a door buzzer. On the C60 the unit was fried and I replace it with a 30 amp automotive thermal circuit. It has only activated once when a wire came loose and shorted out behind the dash. Of course it was at night and the headlights went out.
Cheers Phil