Very interesting. The process you need to follow to isolate your problem is check all your options. I would check if the headlights work with the parking lights, then with the daytime running lights on(if your car has that, you did not say) I would also check the signal lights. Do the high beams work when the headlights are turned on? Knock on the bulbs, do you see a flicker? Before you go wild trying to figure this out, make sure the bulbs are still good. It sounds like the bulbs are bad, or possibly a wiring issue. askpatty.com has great shops you can call to make an appointment.
〉 Answered on Jun 7th, 2010 by Audra Fordin, Owner at Great Bear Auto Shop
Without looking at your electrical schematic for this circuit, I would only be able to guess at the problem. It is possible that your multifunction switch is bad, or that you have a broken wire or loose connection somewhere. It's usually easiest to start at the light and work backwards to find where the voltage is lost to find the cause. Hope this helps.
〉 Answered on Jun 9th, 2010 by Suzanne Grego, Technician at City of Philadelphia Fleet Management