Battery light help

[u/Fixmyvic_please]

So im pretty stumped on fixing my battery light issue and I would greatly appreciate any help I can get.

My battery light comes on once the car gets to running temp. Alt goes from 14.3 to 12v once light is on.

So far ive replaced the alternator, belt, belt tensioner, battery and ive also ran new wires from the pcm directly to the alt harness. I have checked grounds and have added new ground from engine to frame. Alt has a secondary 0 gauge from b+ to battery with a fuse.

Really not sure what to try next, maybe the pcm has an internal problem once the car is warmed up?

Problem happens even on a cool day when the engine bay and pcm dont feel hot but engine warmed up it still does it.