Thanks Cruiser, first I'd like to thank you for your comprehensive guide. I actually just stumbled on it a few days ago and I've been going through it.
I checked the fuse, cleaned the connectors and checked power going though the fuse. All that was good. I don't remember checking for that connection that goes to the NSS but I do know that my dad removed my NSS and we cleaned it up (fixed the reverse lights, now they work). And my dad is very thorough so I THINK that connection was good but I will have to take a second look this week.
Can you explain what this dash rocker switch that says trans control is?
I saw a way to bypass it a long time ago but never tried.
I should also probably mention that a few wires behind the dash were melted together when I bought the jeep, I've done a lot of wiring repairs through the dash and in the engine bay. Previous owner just kind of added wires and switches to God knows what.
Gas tank leaked so I replaced it, also replaced fuel pump and the 3 solenoids in the transmission. All working properly now, except still not shifting as it should, seems like it just prefers to start and stay in a higher gear (I'd say 3rd gear) when in Drive. Takes off like a pig. Manual shifts work great though so I know the cable is working.
Since day 1 I've had this shifting issue, I definitely think it's an electrical issue. Either bad TCU or something with this trans control switch, or a bad ground that I haven't found.
Really wanted to just throw an AX15 in here but I need this auto to work because all my other jeeps are manual and I need my wife to be able to drive me home from the bar 😅