Maybe someone has had the same problem on the truck and fixed it?
The driver side headlight quit working. Put in new bulb, nothing. Checked for juice, nothing. Pass side low beam works. Both sides highbeam works. Any idea what would cause just one plug to lose power?
This is on my son's car so I don't have it here.
I am thinking and ground issue. When he gets home going to check for power again grounding to the motor and see if it fixes it. If not, I may end up haveing to trigger a relay off of the other low beam to kick the driver side on.

 

You'd have to consult a wiring diagram for that car to figure it out, so a shop manual would be handy. But generally, you would need to trace out the circuit from the bulb back towards the switch to find a splice where the power tees off to both bulbs. Theoretically, your open circuit would be between the splice and the bulb connector. Look for some clues. If the car has a dirty battery that drools acid out everywhere, look around and under the battery tray for a wiring harness that is probably getting eaten away by acid. Pretty common.

Make sure you have tested all fuses in the vehicle, and don't assume there's only one fusebox. It's pretty common for cars today to have EACH headlight bulb fused independently of each other as a safety feature.
Hope this helps.