headlight problem

i have a 94 f150 with a headlight prob. i went to leave for work one morning and my headlighs wound not turn on. Every other light turns on and works just fine. Turn signals work just the head lights wont turn on. I changed the bulbs even thought they didnt look blown and tested fine with the ohm meter. checked every fuse in cab and under hood they r fine. changed the headlight switch even thought the other lighs would turn on. does anyone no how many volts there is suppost to be at the headlights plugs?? does anyone have any suggestions about something i might be over looking?? any thing would be alot of help bc the wife is tired of me driving her car lol. thanks 94XLT