'93 Volvo 240 w/ 250k miles: Parking lights work, but headlights/dashlights began to go out intermittently and then went out all together (not fun when you're doing 70 on a highway in rural Maine). Checked the wiring, but it all seems good. Replaced the headlight switch, but that didn't solve the problem. Any ideas?

 

Voltage regulator, battery or alternator?

 

When you have the problem with the headlights going out, do you have your brights on? I had a similar problem with the brights on mine and there is a relay under the hood near the battery that controls the brights. I replaced this relay and it solved my problem.

This would not affect the dash lights though.