I just got a note from someone asking for an update on my transmission saga, and thought I'd post it here for what it's worth.

Last summer I got the classic blinking arrow/WSE lights one very hot day. Changed the PNP switch, but it came back on a few hundred miles later. Ever since it's been happening sporadically; it seemed to run a couple of hundred rpm higher at highway speeds, but otherwise it seemed to shift normally. I took it to a Volvo dealer and they tried to sell me a complete engine and transmission overhaul. I said no, thanks; took it to a local transmission shop the next time it acted up, but by the time they looked at it the lockup was working fine and they just gave it back to me with a shrug (but didn't charge me a dime, unlike the dealer).

A month or so ago I got under the car, took the connectors on the side of the tranny apart, and cleaned them up as well as I can (somebody here suggested that, and I'd tried it once before, but had trouble getting them apart). Since then I've drive ca. 1000 miles with no recurrence. I'm cautiously optimistic that my problem was caused by nothing more serious than a shaky connection in one of those connectors, but who knows?

Jeff