Growing up, every electrical issue seemed to come down to the same 2 usual suspects.. Battery or Alternator.. (or the misc. cables connecting them). So when my wife's Armada battery died, jumped..died, so trickle charged, next day, died while driving, its the alternator, right? Had both tested and they passed!? I cleaned up grounds, replaced the fusible link on the positive cable, checked all fuses and tried again.. this time with a multi meter attached. Battery started at 12.7, and as soon as i start it the numbers slowly but steadily start declining. Revving the engine does nothing. Did the self test trick, just cause it was news to me, first id heard of it.. everything did its thing. 3 codes, P0102 and forget the others at the moment. Oh I forgot to mention 2 things, 10 days or so prior I installed an after market stereo and back up camera, and 2 days before it started the almost no power/dying while running stuff the entire cluster stopped working. My fist time posting, but I have enjoyed and appreciated the work y'all put in here, so thanks for that and thanks in advance for your attention.