Alternator or PCM DUFF?

Hi:

1997 Ram 3500 Cummins 5.9L

Since this morning batteries are both getting deader and deader..

Dash Voltmeter shows about 9V. GEN light is on.
MIL shows 12 code only (disconnected neg terminal months ago re RWAL)
Digital volts (engine idling) at +Battery terminals, Alternator O/P, and both sides of 120Amp Alt fuse is 9.6VDC.

My question:... if Alternator is at fault, should MIL show an alternator code? If yes, then, shudder, is PCM likely duff?

Batteries are charging tonight - we'll do a field test tomorrow. Meanwhile tonight...anyone have experience with this? Help!

Sitka

are you sure your intake heaters aren't switching on when the engine is hot i know they aren't supposed to but this happens at times due to malfunction as these draw mega amounts of current the alt cannot supply enough current and if not you must check your field control at the alt and try full fieldind the alt while idling then rev engine slightly while full fielding alt should overcharge system if working