My wife drove through about 1 foot of standing water and the low beam blew. Actually, the fuse blew, I replaced it and now the high beam works, but the low beam is fried.

I'm not sure if it's the bulb or the ballast. How do you diagnosis which one went?

Thanks,
Pat

 

Swap the left and right side bulbs. If the problem follows the bulb, it's the bulb.

Wear gloves when handling the bulbs as the oil from your skin can cause a premature failure.

You'll need a tamper-proof Torx T-20 driver to access the bulbs.