My driver side low beam went out so I bought the $100 bulb to replace it and installed it tonight, but the light still won't come on! I'm pretty sure I installed it correctly and put everything back together right. I checked my fuses under the dash and they're all good. What's going on here?

 

swap the known working bulb into the problem side. If it doesn't light up then you have a bad ballast. Very common problem, tons of info on this site.

 

most likely the ballast is the issue, not the bulb.

I'd get a new kit from Morimoto and call it a day.

https://www.theretrofitsource.com/ma...epair-kit.html

 

Been through this issue on my 2002... turned out to be the igniter.

That's the part that plugs into the bulb and the ballast. It is available separately from the ballast (which fail much less often).

Very expensive $$$ from Honda but $ on ebay. I've used both w/o issue.

Easy to diagnose - examine the socket that the bulb mates into. If the plastic "fingers" that hold the metal contact in position show any indication of melting and/or oozing in that area, then replace the igniter.

My "bad" igniter worked fine when tested outside the headlamp assembly. Once installed it would fail to ignite. Drove me nuts for two weekends.