[JRTJH]

There are NO stupid questions, so ask away....

Yes, it is functional with/without the battery cutoff switch. For safety purposes, the brakes are directly wired through the breakaway switch to the battery positive terminal. That way, there will ALWAYS be power to the brakes regardless of what the owner might do or forget to do. There is no "switch" to control brake power other than that plastic pin that inserts into the breakaway switch. The only way to turn the brakes off is to disconnect the battery cables or insert the pin.

Next time you're at your trailer, take a look at the breakaway switch wires and you'll see that one goes to the trailer brakes and the other goes directly to the battery (possibly connected at a 30 amp circuit breaker "INPUT" terminal).