problem with cluster lights

[Firefly]

I start up my car and sometimes the coolant, parking brake, and battery lights stay on for a few minutes. I checked the voltage readings for the alternator thinking that it might be failing and the voltage drops about 2V when the lights are on (goes from 13V to about 11V) but goes back up to normal levels when they turn off. I already looked at the coolant level and the battery, both seem fine so it's giving me false errors. So far it doesn't seem to be affecting anything but I dont want to wait around until it does. This started up about a week ago and I haven't installed anything in a while so I don't know what could be causing this. Anyone run into this problem before or know what might be causing it?

 

[Black_Stalon]

maybe try disconncting one headlight system at a time, perhaps one of your lights is bogging it down, but if they all look ok, i would assume your alternator is on its last legs.