07 suburban electrical problems

[Csanders2]

First of all sorry this is the wrong forum. I couldn’t find the correct one. Kinda of a long story but I’ll try to keep it short. About two years ago I started having problems with oil pressure dropping to zero. Talked to a few mechanics that pointed me towards the oring on pickup tube and the oil pressure sensor. So replaced em both just to be sure. While is replacing them I was listening to the radio on it.  It ran the battery pretty low.  Almost done with project I need something out of the back so I pushed the button on the back to open the rear tailgate. Halfway through the battery died. So I get the battery charged back up. Now I non longe have use of the rear tailgate and the shift indicator is only working in r d and 2. Figured I fried a computer I took it to a mechanic. Who told me that most likely the bcm is fried. Ok well moneys tight right now so it’ll hafta wait. Here we are two years later and I have the money so I get the new one programmed and installed. Still a no go. So I borrow a scan tool. Turn out it’s not getting signal from trans switch p. So I discover the wire going from the switch to the tcm to the switch is bad. So I fix the wire. Still not getting signal. So my question is how is this signal moved after it goes into  the tcm. Okay never mind problem solved. Never thought to check the harness for another white wire. After repairing the correct wire everything is back to normal