Alternator or something else? If everything is on (lights, radio, climate control) the lights pulsate as do the interior lights. The voltage meter on the dash moves to the left of 14 about 4 hash marks.

 

I replaced my alternator with a re-manufactured one and about a week later, I started the truck to leave work and everything was flickering to a rhythm. I was watching the voltmeter pulsing like everything else It did that half way home then quit charging. When I came back into town it started working fine for awhile. I took it to Oreily's and they said it was a bad regulator in the alternator. Hope this helps...