1993hiluxsr5

hey, i have a 1993 toyota hilux sr5, 2.8D manual.
i have a question about the 4wd button on the low range gear stick.

This is what has happend in most basic terms, my 4wd stopped working (locked on with diff lock) and it was a result of either a relay or a solenoid, and toyota wanted way to much money to have it repaird, so i made my own relay circuit and this disconnects and connect the 4wd lock perfectly.

the only thing is, when i click the 4wd button on the gearstick i hear a motor sound comming from the transfere case and again when i unclick it, but the car is still in 2wd mode, i know this becuase i took it on some mud and floored it and it was rear wheel drive no matter if the button was pressed or not.

then when i click MY 4wd lock switch its in full 4wd, but the diffs are locked, this is what i was supposed to do when i made the circuit , but my question is, what the hell does the button on the gearstick do ?

i havnt touched it at all so it is still at factory settings.
so is this button supposed to give me 4wd without locked diffs ? or is it something else in the transfer case ? because at the moment the only 4wd i have is with locked diffs and through MY circuit.

any help will be appreciated as i am stumped :S
thanks.b