When I turned on my headlights and fog lights yesterday, both the passenger side low-beam and fog light went out at the same time. Every other light in the headlamp assembly works fine and all other exterior lights are working. I pushed the headlamp socket in all the way (of course that would not resolve the fog light problem) but it didn’t work. I checked the fuses in the headlight module and all were good. What could cause that?
FYI – I’ve installed Lasfit low and high beams and fog lights.

 

I think its your LasFit lights - just swap them from side to side or put the original bulbs in and see if they work.
Now, the ground for the passenger side lights you mention is at G101, this includes the ground for ALL lights on the front right of the car. If that side's high beam and turn signals also won't work, take a look at G101, it's the bolt/eyelet hidden under the washer fluid filler tube on on the passenger side under the hood.

But I really think it's those aftermarket lights, SO many people have issues with them. I dont see what else it can be, the low beam and fog light are fed by different fuses.

 

Thanks! I'll check out the LasFit bulbs. The high-beams, turn signal bulbs and front position bulbs all work so apparently it's not the ground. What bulbs do you use? Original incandescent halogen or other brand of LED bulbs?

 

Needswings sells PIAA 4000k bulbs. I've used them for over a decade. They work great. Sylvania sells a good bright bulb also for considerable less money. Both are H7 and slip right in. Neither are LED so no problems.

 

Well, I replaced the both of the LED low beam bulbs with incandescent H7 bulbs. After they were in I turned the lights on to see how they looked and found that neither of my low beams were working. All of the other bulbs in both headlamp units are working. Both incandescent and LED low beam bulbs are now not working. Could it be my illumination module (headlight switch)?

 

Use a volt meter and see if you have 12v at the electrical connector; Check the fuses if no power. If you have twelve volts then the contact is no good at the bulb/ground. Bulbs should have continuity.

 

The fuses are all good. I'll check the power at the connectors but It is hard to believe that the passenger side LED low beam went out and when both the "bad" and good LED low beams were replaced with brand new incandescent bulbs neither side would work.
The driver's side and passenger side low beams are on entirely different circuits.
I figured that the one commonality would be the low beam position on the switch (illumination module).