OK...this one has me confounded.
I've got the new style post-recall switch in my car, and actually have for several months (verified the pn with the dealer.)
I've been running without DRLs for quite some time now. This past Friday, the bulb out relay activated when I put the headlights in the "on" position.

After cursing, I got out and checked. Nope, the headlights were working fine.
I re-verified that all the other bulbs were ok, and that the bulb out light went off when I turned the switch to the parking light position. So, I figured, the problem must be with the headlights or the switch itself.

Here's where the mystery deepens. If I flip the screw over to the DRL position, the headlights (and all the other lights) come on, and no bulb out warning! Flip the screw back, though, and I've got the warning light.

WTH?

Are there ANY exterior lights on the S70 that are lit:

1. without the DRLs on
2. Only when the headlights are on, and the headlights are manually selected via the switch
3. are NOT the headlights themselves?

Oh, brickboard sleuths, I've got a mystery on my hands!

TIA.