Thank you for the advice! I was able to work around the HV cables and didn't die haha.
Gentlemen, I may have named this post incorrectly. The problem may have been a combination of issues.
The dealership replaced the negative cable but did not replace the Positive. I found this weekend that my positive cable terminal was not making a good enough connection to the 12v battery. I found the terminal cracked from underneath where the + cables are bolted onto the battery terminal connector, I could see shiny coper at what seemed like a seam, wiggling it or bending it gave the no crank/good crank symptoms. When I would remove it to charge the battery and plug it back in, I'm guessing it was hit or miss and sent me down the wrong rabbit hole.
Apparently when I did the test recommended here to see if the battery was charging, I had it connected in a way that it had a good connection and was giving me what I wanted to see but not what happens if the terminal is moved a certain way. This would explain the system not being able to charge the 12v batt correctly previously and making the terminal way hot to the touch. HINDSIGHT
I still need to check if the truck continues to use between 60-120 mA spikes while its asleep, but all calculations say that high of a draw would take between 8-14 days to kill a battery just sitting. I could live with that. We use it almost every day.
Secondly, I found a short in the wire loom that goes to the HV controller under the hood. I think I saw a TSB on this about checking the loom for cutting from the metal band that holds the loom which is bolted to the passenger side head ( right around the heater hoses!! ) . I found 2 cables that were slighly cut into. The plastic cable management was burned from one side and not visible from a basic inspection with the intake tube off. Two of the cables were slighly cut into from the metal band that holds the loom and the other appeared to have over time had the sheath cut from one of the retaining clips holding the electric motor that feeds the in/out heater hose lines to the water pump. Electrical taped the cables and checked for other cuts and that was it. Retaped the whole loom and put the cable management back on. Kept the metal band but folded it in a way that will not cut again and used some zip ties to better hold the weight of the entire loom. Started the Tahoe and wiggled to test and the issue is no longer occurring where HVAC controls lock up and airbag light illuminates for a few seconds.
While I wait for the OEM positive cable assembly i used a spare battery terminal that I had and bolted the positive cables to it. Left it plugged in overnight and started just fine this morning. Will continue to check 12v battery voltage over the next few days of usage and will provide another update as I get more info on this nightmare.
Appreciate all the help!
