Alternator
 

I have been noticing at night that my lights (all of them interior and exterior) flicker rapidly with the rpms and the voltmeter in the dash fluctuates slightly (14.75V to 15.5V approximately). The flickering is worse when you rev it up. I bought the car with a pair of 12" alpine subs and an amp and all of the other speakers are run from another amp. Supposedly the stereo components were installed professionally. Is this a sign of a failing alternator?

Does it do it with the stereo on? Take it down to auto zone or advance and they will test the whole charging system for free A bad battery can cause that too, as can a short somewhere