wow, thanks, those are going in my ever-swelling file of Volvo info.

Played with it some more, and there's nothing wrong with the relay or the lock motors. If I jump wires between those three plugs on the car-side of the connector, the doors lock and unlock perfectly.

So I guess either the little round switch is bad, or I did miss a bare or broken wire? If I can figure out how to run a little current through the switch/wires and hook up a tester, what kind of numbers would I be looking for?

Sometimes when I hook it all up, there's a little bit of juice getting to the locks -- enough to make the relay click when I push the driver-door button down or up. Oh boy, I've tried too many different things too many different ways to remember exactly. Shoulda written everything down.