Ef 2 trans in AU1 Fairmont in limp mode

[trublu1]

Hi,I recently replaced my auto trans from my 1998 AU1 Ford with a auto trans taken out of a Ef 2 Falcon.After we finished the swap i took the car for a test drive and i noticed that the transmission was in limp mode but then i would leave the car for several days drive the Ford again and the gears would change great then all of a sudden it would go into limp mode again. The person i purchased the trans from assures me that the transmission was in great working order and that i have no reason to disbelieve him. So with me putting the EF2 trans into my AU1 Fairmont shouldve ive changed something else like a computer,relay or something else?