A maze with no exit (brake light wiring)

[misterprofessionality]

The aftermarket light does have both functions, based on the fact that the bulb has two separately actuated filaments.

I've seen all the wiring diagrams, but i can't make any heads or tales of it other than to say i think you should be correct that the green/yellow wire delivers power from the brake switch.

If the black/brown wire delivers power to the running tail light, then why can i get no operation at all whenever it's hooked up to either wire?