Pcm interchangeability?

[IowaCumminsCB]

Hey so for a while now I have been having a shift issuewith 1-2
Shift from 1 to 2 will be fine under low load
But under load it will shift to 2nd then quickly drop back to 1st then sollidly shift to 2nd and have no problem after that. Well we figured out command pressure is indicating a 13-18 psi drop in gov pressure.
So we were thinking either valvbody or pcm.
So my guy was going to build another valvebody to test it out and if still acted up might be the pcm
Well last night the glitch turned to a failure
Was running fine when I went to work then went to go home and no Od and 1st gear was loose like a high stall tc.
All codes are looking like possible ficim or pcm.
Which I am happy that it finally failed so I can have a good shifting truck back but my question now is can I purchase a used pcm and install it and work? Or have to flash it or do I have to purchase new?

 

[Scooter's Roofing]

you can install a used one

 

[IowaCumminsCB]

Ok that's what I thought
I have had one guy say no Ya can't then the guy that's doing all the work said Ya could

Also anyone ever had the issue with the od off button working intermittently?
Like one day you could use it it will shift out of lockup and od and stay
Then another day hit the button and it will go out of lockup for 2 seconds then go back to lockup?
Possible pcm?

Another thing yes another Is the gear selector if Ya throw it into 1st then manually shift.to.2nd and it not go? It will hold 1st till you shift.to.drive and letoff throttle a tad?