Migrating this from the "bloody blower motor"/fuse 8 thread.

I've pulled the ignition tumbler/lock/switch mechanism.
Before I examine that, I'd like to make sure 15x is getting juice.
From what I understand, the key is what activates this circuit, meaning that if I stuck a multimeter onto the 15x plug on the connector and reconnected the battery, it would probably read cold. Am I missing something? (everything?)

How do I test circuit 15x, if it's only turned on through operation of the ignition switch?