i was working on my car today (96 cavalier 2.2) and i noticed a faint humming/buzzing noise (CAR WAS NOT RUNNING OR IN ON POSITION). I tracked it to the alternator, if i unplug the alt, the humming stops and if i plug it back in, it starts up again. If i unplug the battery and reconnect it, it Doesn't mak the noise until i start up the car again. anyone know what it could be, or if its important to get it fixed?

Well Croatian Z24 : Alternators do make some kind of noise, What you want to do is get a multi digital meter, while the car is idling place the positive and negitive leads to the car battery, to see if the alternator is working properly and charging the battery, Usually what happens is their are little carbon contact brushes that allow the current to flow through the charging system, They are prone to make noises when things get old wornout. I believe the multi digital meter test would be youre best trouble shoot.

Good Luck.