Thanks. I figure I'm going to get a new switch while I'm at it. As I understand it, a lot of 850s had headlight switch problems (I think the heat under the dash weakens the plastic -- I've got mine held together with strapping tape). I'll get a voltmeter and check the plugs as well -- and use the ohmmeter setting to check whether the ground is working. That might be the problem with the right-side running light as well, but I'm afraid I'm going to have to get a whole new light assembly for that side (I bumped into someone and shattered the lens -- the light assembly got exposed to the elements and rusted quite thoroughly).

As for the switch, I assume that there's actually supposed to be an "off" position, right? As long as we've owned this Volvo, none of the three positions actually turns off the headlights. They only go off when you're in-between positions.

You'd think there would've been a recall on something like that!