Hello and thank you for choosing just answer.

So your headlight is dim on the driver's side only correct?

Also does your vehicle has a 2 bulbs on each side or one bulb on each side?

I mean does it have a seperate bulb for low beam and high beam? or one bulb does both high beam and low beam?

Let me know so I can help you better

So it is significantly dimmer than the other side? but high beam on the same side works ok? OK, do you have a volt meter so we can do some testing?

If you have a volt meter then we are going to do some testing on the side that is dim. in the connector that has the headlight you will see a black wire and 2 other wires, I would like you to connect your black voltmeter lead to the black wire and with the red meter lead test the other 2 wires while it is connected to the headlight and the headlight being on. See what does the volt meter read on both wires and give me the colors of the wires that you tested and what voltage did you observe on each one so we can determine the problem.

OK these readings are showing normal voltage to the bulb. the brown wire which is in fact orange in the diagram is getting 13.56V which is the positive to the low beam bulb and the black wire is ground which is 0.46V which is acceptable. I think your problem is with the reflector in the headlight assembly itself and not the bulb. I think this answer will not make you happy. If you are not happy with my answer let me know and I will opt out of the question.

Opting out of the question will re-open the question so other experts can help, But I am positive that the problem is not electrical and rather with the reflector in the headlight assembly.