Trans limp home mode

[Fr0zEn]

I have an 89 240sx I put it in drive, works normal but only in 2nd gear, no 1st 3rd or 4th gear. I have changed the transmission and no luck. so 2 transmissions same problem. always good to have a backup. but anyways. How do I get it out of limp home mode? I tried disconnecting the battery to clear codes and that wont work. any help is greatly appreciated.

[OutToWinPAHC]

ECU possibly? Insert 5 speed here light on?

[Fr0zEn]

yeah the 5 speed light on but that i wont make it through another salty winter is on too.

[OutToWinPAHC]

I say its whats controlling the trans. The chance of 2 doing the exact same thing are kinda slim. I say its the ECU, are you using the same converter with both? Check the trans lines to the radiator and check for blockage.