What is supposed to happen when my Subaru's test mode connector is hooked up?

There’s an electrical connector under the dash of my 2000 Subaru Forester that is apparently instrumental in the diagnosis of some OBD-II trouble codes. It’s a pair of bladed terminals like any other on the car:

Specifically, some of the diagnostic procedures in the factory service manual call for testing several evap system valves in turn like so:

1) Connect test mode connector. 2) Turn ignition switch to ON. 3) Operate drain valve.*

It was a little scary, actually, the first time I connected it and switched the key on — the fans spun up every second or so, I could hear relays clicking all over the car, and the MIL started flashing.

But I’m not sure exactly what I should be expecting to happen. Is there an implicit sub-step to item 3 above — “Operate drain valve” — that I don’t know about?

Or is the valve being operated just by putting the car into test mode? I applied a stethoscope to one of these valves that’s easy to get to and it seemed to be clicking open and closed, and passing air. Is that all there is to it?

If so, which valves are supposed to be operated in this mode? Drain valve? Shut valve? Purge control valve? Pressure control valve? Literally every electrical component on the car? I can’t really say “this valve is dead” without knowing for sure that it should be switching. Is there a list in my FSM somewhere I haven’t found?

My car’s a 2.5 liter, SOHC, manual transmission, USDM.

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*For the curious, this “drain valve” is PN 42084FA120, and everywhere except my manual calls it “canister ventilator valve”.