Hello all new here to the forum and I'm having an issue with my newly purchased 6.5l Naturally aspirated 4l80e combo in a '95 Air Force box truck. I bought it from a friend not running as the battery's we're removed because of a charging problem, it would drain a battery left not running for 3-5 days. The truck has 42000 miles on it. Before getting it running I replaced 2 pulleys the serpentine belt , fuel filter, oil cooler lines top and bottom, oil and filter and soddered alot of wires that rats had eaten away at pretty badly. Truck fires right up after purging the injectiors and 2 new 600cca batterys ran good and idled pretty rough for 20 minutes I added alot of Lucas and some farm diesel and it cleared up.. come test drive time it seems the trans isn't shifting either out of 1st or out of 2nd I have reverse and 1 forward gear so I come back drop the pan and it's nasty brown pink and like water thin no burnt smell just really old fluid so I replaced filter added 5 qts and tried it after that it shifted great for 2 weeks I go out of town for a week and the truck won't start again and battery's we're reading 6 volts I charged everything up tightened up a not so snug ground on the front battery and it started up now the ses light is on and wouldn't you know it back in damn limp mode.. I drove it to a local auto store and where over the phone they assure me that they have an obd1 reader so I lug it a few miles to the parts store trans hit 230 on the gauge(mechanical autolite) measured at the outlet of the trans pump. They couldn't read my vehicle on their reader so fusterated I drove it back home trans at 210 for 5-7 minutes and shut it down...next I tried the paperclip meathod by jumping terminals a and b on my 12 pin port and nothing happens no 12 code no nothing the ses light just remains on so in vein I pulled the pan off the transmission again replaced filter and changed solenoids a and b as well as the vss input sensor on the side of the case slap it back together and nothing still in limp mode...I checked the plug and I have one pin hole of the plug that reads 12.4 volts so the transmission has one hot location on the plug is this correct or shouldn't a few other holes show hot? I've checked the wire for breaks and chaffing and everything in between. What can I do to get this thing out of limp mode?(an assumption) it's also worth noting that even though the truck won't up shift no matter what gear I have it in if I pull it from drive into second it kicks down like it was in gear but it's like that gear doesn't exist and it will only kick down if it's very part throttle if I'm accelerating and shift it manually up or down it does nothing reverse works flawless and engine is very responsive and alot of torque but it's just not upshifting. How can I read the codes or at least reset the 4l80e to get it out of limp mode? I've taken the negative terminals off and let it sit for 10 minutes to 1 hr and each time the ses light returns and it's still limping. Any help or advice is greatly appreciated and one local shop said they have a quality obd1 reader but if they can't read it it'll still cost 80$ which is sort of crazy to me but they're almost the only person in town that will even look at it. I'd love some advice because it's on me now I'm running out of dough to throw at it need this truck to haul my family and our belongings back to Houston 500 miles away. Thanks again!