One low beam not working. Not bulb, not fuse.
 

2002 Boxster with standard (non HID, non litronic) H7 55w low-beam bulbs.

My passenger side low beam is not working and I cannot figure out why. All other lights (driver side low and hi beams, fogs, etc. work fine)

Here is what I do know. It is not the bulb. I replaced the driver and passenger bulbs with brand new ones and the passenger side low beam is still not working. I also swapped the plug connectors at the back of the bulb between the low beam and the hi-beam as a test. When plugs were swapped to test, the low beam light came on and the hi beam did not...so clearly not the bulb. It seems no power is getting to the plug at the back of the low-beam bulb on my passenger side. I do not think it is the switch on the dash. I installed a brand new switch last summer, and all other lights are working fine. Besides, if the switch was kaput wouldn't both (passenger and driver) low beams be off? It is not the fuses. I swapped fuses A9 and A10 and also tried one of the larger (25 amp) spare fuses at A9, no change, same thing, passenger side low beam not on, all other lights fine. That's about the limit of my electrical know-how to troubleshoot this. Did a search a found lots of people with light issues, mostly bulbs, switches, and fuses, but couldn't find anything with this exact issue. Is there some sort of relay that I might need to check? Any guidance is really appreciated.

Check the relay?

Is that supposed to be a statement or a question?

Take your pick, but check it if you haven't.