My passenger side regular light won't illuminate. The high beam works fine and the parking light works fine but the driving lamp won't light. I went to change the bulb and both fillaments are intact so I tried a new bulb just to be sure and nothing. Anyone heard of this before?

check your fuses

Swap different components of you lighting system between the left and right side individually to check which one is faulty.

Sounds most like there's a break somewhere in the low beam line between the headlights. At least, that is, assuming that the bulbs you tried don't actually both have bad low beam filaments ;) (sometimes you can't tell visually). Putting the left - working - bulb in the right light should eliminate that issue...

Assuming no bulb issue, this should be easy to test with a meter:

unplug both headlight connectors
find a couple of small nails, pieces of wire...whatever, that will fit snuggly - but not a forced fit - into the connector
put one "adapter" into each connector, in the socket for the Yellow/Red wire
connect the test leads for the meter to the "adapters" and check for continuity

If there is no continuity then the line is broken somewhere in the harness between the 2 connectors, which runs underneath the A/C condenser, below the lower grill opening. (This may mean that other lines in the harness are at risk as well.)

The solution would be to bypass the broken line with a new length of wire...but doing it right will take a bit of work. You can cut the Yellow/Red lead near the right connector (strip the harness sheath back to free several inches of wire at least before cutting). Verify continuity between the cut wire and connector socket, i.e., make sure the socket itself isn't the problem! (If it is, then source a replacement - junkyard, leftover harness parts... - and splice it in to the harness.

You'll also need to carefully cut open the harness where the left socket lead meets the main harness, exposing the same line - on the side between the headlights. You can then cut the exposed line, leaving several inches exposed next to the left connector junction. At this point double check the continuity from the cut line on this side to the left connector; if nada, you'll have to expose the actual junction itself, for a 3-way repair.

To finish the job splice in a new length of wire to connect the 2 cut ends. (I'd use 16ga.; no reason to be marginal here, even though the orignal wire is probably smaller). Ideally this should be soldered connections, with shrink tube to cover. If you're feeling crude - and lucky :p - you could use a couple of Swenco "Posi-Lock" connectors to make the connections.

If you haven't done this kind of wiring work before see if you can find a friend, and/or another local Subie person who has to assist...