4-wheel drive problem

i own a 98 ford ranger 4x4..and i dont know why but it will not shift into 4wheel drive..at all..its just a little knob on my dash that i turn..but i wont shift..i dont know if its electrical or what..if anyone has any ideas on what the problem could be i would apprieciate the help..thanks

the electronic shift solenoids are notorious for going out but i would check all your wiring first.

The 4X4 shift module is located in the passenger side kick panel. The 4X4 shift motor may also be bad or a bad wiring connection.