Way the heck back last year I wrote:

Hey, better late than never: I finally got back to this last night...

The answer is: A dislocated pin in the 4-wire connector at the base of the turn-signal lever, where the pigtail from the cruise-control switch plugs into the little 4-wire ribbon lead that goes down the steering column. Needless to say, I didn't discover this until after I'd disassembled half the underside of the dashboard to troubleshoot the harness down there and find nothing wrong with it, but whaddaya gonna do...

Anyhow, turns out that when I plugged the pigtail lead into the ribbon lead at the base of the turn-signal lever, one of the 4 pins in the socket didn't line up right, and the pin and wire got pushed out the back of the connector. It'* a really tiny wire and I didn't notice it at the time. I finally got it all assembled properly last night, and I can now go on long trips again without having my right foot fall asleep!