Gen 1, Auto-Shift, replaced X-Y shifter, now won't shift out of 3rd gear

Speed sensor issue?

 

I have 3 trucks that originally came with auto shifts and ended up converting all to manual. Nobody knows how to work on these trannys anymore and it's a big pain to diagnose.
The most common problem I had was transmission wiring

 

Go on the Eaton website. There are complete troubleshooting manuals, how to get codes without the software. Just have to know how to read and follow simple instructions and use a multimeter. Manuals are free to download. Can't post here because the files are too large, tried it before, some are almost 400 pages. I would closely check all the wiring at the trans, pull apart the connectors and look for corrosion. Might be a module issue. You can also call Eaton for help with diagnosis.
The Autoshift have the same guts as the manual trans. Just that the autoshift is controlled by computers.

 

I can give you info on shops in Detroit and Chicago, who can do it. Pm if you need.
You basically need a new transmission top plate ($500) and a meritor electrical 10 speed stick ($200 at a junk yard). The rest is labor, dropping the transmission, making a new harness, reprogramming the ecm (depending on the engine). Might as well throw in a new clutch.
I did my last one like 3-4 years ago and all together it was under $3k. Might be a bit more expensive now, since price of labor went up.
There is also a possibility that your tranny itself needs a repair. I suggest to not waste time and just get a rebuilt exchange for like $3500 instead of tearing old one apart. I bought mine from Valley Truck Parts in MI

 

what transmission do you have? I also had a 2001 pete with an 18 speed autoshit. I converted it and was much happier.
parts needed.
New transmission case, couple sliders and maybe 1 gear. used top plate and shift tower, simple parameter change in ecm and probably disable a neutral safety switch( I didn't know that and just ran a new wire to starter)
inland truck parts did my conversion. he just looked at the parts list for the auto vs manual and changed anything that was different.
I can give you more details if you have the same transmission and are interested

 

yup same exact setup I had. the difference in the case and the reason you have to buy I different one is a single missing hole. the A/S case doesn't have a hole for the lockout pin for the range shift(something like that anyway, my terminology may be off. but basically it's what keeps the transmission from trying to shift range while in gear and destroying itself.
most autoshits came with a solo, self adjusting clutch, they are garbage. if it still has one, get rid of it!
I did this probably 10 years ago. cost me 2-3k then. for me it was Well worth the cost. I removed and replaced transmission and had a shop do the actual transmission work.

Inland truck parts. sioux city, IA. ask for Doug. he knows his stuff.
but like I said before a simple comparison of part numbers is really all anyone needs.
reused most all my original gears and bearings.