My boyfriend just replaced his driver side headlight a month or so ago. The new headlight is already dying (or it is at least dim enough to look like it's dying) any idea why this might be happening?

squealing is cased by the belt getting warmed up or it might be the idler pulley

Thank you, do you have any ideas as to the answer of my other question?

I need more explanation of the problem

His driver side headlight was dying for a few months and was almost dead then he replaced it. And literally later that same day as he replaced it he noticed it was slightly dimmer than the passenger side (just by looking at the lights on the road at night). He's only had the new headlight for about a month or so. And I noticed about a week or two ago that the light was already dying or just really dim. I'm thinking it's the driver's side headlight fuse (if there is such a thing) and my mom thinks it's an alternator. Is that explanation anymore helpful?

yes the alternator would cause both of the lights to dim but it wouldn't do just one but the fuse is such a thing it should be in the underhood fuse box the diagram of where the fuses are is on the b ottmom of the cap there should be a fuse that says LH headlamp if it is good and doesn't change anything get back with me

How will we know if the fuse is good or not?

if it is broken on the inside it is bbad if it is not it is good