Automatic gearbox issue

Hy all, my name is Sergiu and this is my first post on this forum so please bear with me
I have a 2003 jimny automatic witch i use it mainly for off roading, recently i swap the transfer box with a rocklobster transfer box ...now i could never refit the speedo due to the fact that the rocklobsters speedo drive is mechanical and original jimny transfer box is electrical...Now my gearbox fells like is stuck in second or third gear , so my question is does the gearbox need the vehicle speed imput to work or it work regardless and i have a diffrent problem ?!
Thankyou

Yes! The automatic gearbox control needs a vehicle speed signal.
When automatic gearbox control units cannot operate they are designed to go into limp home mode, usually 3rd gear and reverse.

You could connect up an aftermarket sensor but I've never had to do anything like that on a Jimny.

Thanks for your replay
another isue i have is that my ecu went bad so i had to replace it, since the auto jimnys are rare i had to get an ecu from a manual jimny ....engine works ok but the auto box TCU is not receiving any imfo from the throttle position sensor and the box shift verry funny
Are te ecu's diffrent manual to auto.?
TCU gets its TPS info from engine ecu or straight from the sensor ?
Verry litle info on auto jimnys....