Like the title says, I've got an issue regarding the passenger side headlight. The bulb is fine, and all the fuses are. Do you have any idea what could be the cause of the problem?

I've tried new fuses (2), and new bulbs (3), still isn't working out.

Mazda 3 sport GT 2005

 

use a volt meter & verfy voltage is getting to both sides of the fuse, then to the headlight... that will let help target the problem area.
The lights do use seperate grounds, so it's possible that rusted off on the passenger side only. It's also possible one of the relays died that drive the headlights. The relay for the headlamps is either in the passenger junction box (I know that's where the high beam relay is) but it could be in the fuse/relay box near the battery.

 

I have the same issue, but on the driver's side, I took the old bulb out, and it was burnt however. I put new bulbs in both sides, but the drivers side was still out. I put the old good one back in the passenger side (as to not test with my new bulbs) and it still worked there, then I put that bulb on the driver's side & nothing. I'd like to find the relays for the headlights. Le me know if you know where they are, and how you resolved this issue. Thanks.

 

open the hood of the vehicle and you can find the relays inside the relay box on the driver's side. It will be situated near the battery box.

 

Correction, the headlight relays are in the PJB (passenger junction box), which is located behind the glove box (can be accessed from underneath it). The low beams are both driven from one relay, the high beams are both driven from a second relay. Each individual lamp has its own fuse in the PJB.
If only one low beam is dead it is a fuse (or the lamp or broken wire)
If only one high beam is dead, it is a fuse (or the lamp or broken wire)
If both the high and low beam on one side are dead, it's a bad ground.
The light assembly has a drivers side ground (front side of the battery box), and a passenger side ground (near the #3 engine mount).

 

Im having the same issue. Had a burnt passenger headlight on my 2007 Mazda 3 GT, changed the D2S bulb out to a brand new one and it was still not working. Just to ensure that the bulb was in working condition I swapped the bulb with the the driver side and it worked. Since only one of my lights is not turning on I have ruled out a relay issue. I checked and all my fuses are good. Im guessing its the ballast (Ballast control unit module computer) any thoughts?