Alternator going bad or what?

[Willie 66]

Hey all,

Got an '02 Sierra 1500. With a warm engine sitting at idle around 500 rpm and exterior lights on (nighttime), my interior lights on the dash flicker a bit. I have just over 14V, but if I put any amount of additional load on the electrical system (blinker or power windows), it *really* becomes noticeable and I can see the needle on the voltmeter dip down to 14V or less. Even in daytime, I notice the gear display light and the "message center" LCD screen flicker a bit. Problem goes away at anything above idle.

Just wondering if this could be indicative of something starting to fail. No troubles starting the truck. Just replaced plugs and wires last weekend. Changing belts tomorrow. Could it be the belt slipping on alternator pulley? The belt squeals a bit on cool mornings, but never the afternoon. Or is this a symptom of an emerging alternator/battery issue?