Volvo: Volvo headlights, fog lamps, volvo 240

Question
1987 Volvo 240 - wonderful car to drive!

Sometimes the headlights will not come on, although the fog (?) lamps still work. When this happens I believe that the turn signals also do not work - and some of the little warning lights on the dash. However, the brake lights (important)
DO work.

Any thoughts on where to begin trying to fix this problem?

Thanks, David

Answer
One thing to check is whether or not you're getting voltage to the headlights.  If you're not, it could be a short or frayed wire in your wire harness, or a malfunctioning headlight switch inside your cabin.  Another thing to consider is if moisture is related to the failure; it could be water accumulating in the front lamps that causes a short.  I would carefully trace the headlight wires back from the lamp itself.