H3 electrical issues

Hello everyone. Newbie here. I have a 2006 H3 3.5l with tons of codes. I'm a bit mechanically savy but know 0 to non about electronics. Hummer won't start without jumpers. I've replaced battery and alternator. A few corroded relays and fuses as well. Hummer will stay on until I put it in drive then it shuts off. I have a scanner. I've attached pics of codes. Any help will be greatly appreciated. Thnx a bunch

So it doesn’t do anything until you jump it? What’s the alternator putting out at the battery terminals? Do you have Power at the alternator stud??

Yes it does have power to post. It reads 11-12v. Hummer stays on until I press brake to shift.

Does anything happen when you try to start the vehicle prior to jumping (starter engagement, relay-solenoid noises/clicking, etc)? 11-12V running sounds pretty low. Don't know if that has a smart alternator, but put a load on her (headlights+blower+rear defrost) and take another V reading. If it stays the same (or goes lower) something's amiss.

Why was there corrosion on the fuses and relays, you mentioned?