06' avalanche electrical 'BUG"

06 Avalanche 5.3 4wd 85k miles, here's my long ass story. this is a 3 or 4 month troubleshooting headache for me so ill try to describe this as its progressed and make sense of it.

hopefully folks reading this don't take offense but i cant help but say first off i'm not looking for any replies saying "check the fuse" or "its the switch, did you check the switch" and etc. lol. but for anyone with actual knowledge and useful advice that can help me i thank you.

1st- bought the truck in "perfect" working order about 7 months ago, then around 3 or 4 months ago the 4wd started intermittently going in and out of working. at first it would go out only for a few hours or for the day and would usually work after sitting overnight. Heat related slash electrical component failure when hot or something along those lines and then pretty much went out all together. checked components and thought i had it "figured out" after cleaning and inspecting and reinstalling just about every ground terminal and strap on the truck except i didn't do the NEG. cable at the block mount, and i didn't do the POSS. at the solenoid. i didn't do any of the interior ground blocks up under the dash, i believe there's one on each side on the firewall way up in the dash? after the ground fixes it was working for a few weeks and now its back to playing dead again for a few days now.

2nd- around the same time the 4wd started acting up i i noticed the door ajar trigger wasn't working on the drivers door only. it wasn't illuminating the interior lights when its was opened or shut but it would shut off the rap delay when opened like it should, and if i locked it and then unlocked it through the window down and opened the door the alarm would go off. all the other doors were working perfectly so only the drivers door was affected. "coincidentally" after cleaning the grounds for the 4wd system it started working properly and it is still working now even though the 4wd isn't. i know there not related with each other than maybe by ground or the data link but i bring it up cause I'm leaning towards an obvious ground distribution or data link problem.

Lastly- also the DIC button on the steering wheel isn't functioning, removed and checked buttons with a meter and its good, fuses good, all other buttons for the audio, horn, fuel data and odometer are working fine. so just the one button for the DIC doesn't access the programming menu. I've only used the button one time and that was when all this started and at that time it worked fine, so fast forward and it hasn't been working since around the same time the 4wd originally went out.

i've researched what i can, i think i can rule out a bad drivers door module.? the drivers door trigger is seen and controlled by the drivers door module, the passangers by the passanger module, and the rear door by the BCM. it having been the only door with the problem thats a no brainer but with it fixed now after repairing a weak ground and all other switches and things working i dont think its the cause for DIC issue. the truck scans fine with no codes. anyone know if the data link might be the problem for the DIC and maybe even the 4wd.

also after messing with the grounds it seems the shift points are noticeably different for the 1st to 2nd shift. its holding in 1st for a few seconds longer before it up shifts. and it tends to stay in 2nd around slow speed cornering when is should downshift to 1st. im talking about 4-5 mph and it refuses to downshift to 1st unless im heavy in the pedal, then its overkill with the acceleration burst. trans fluid is good condition, shifted fine before all this B/S with the 4wd and tcase fluid is fine etc.

thanks for any help..