4X4 PROBLEM S10 BLAZER

HI THERE.I READ WHAT YOU SAID ABUT THE WIRES ON THE BLAZER,BUT MINE WE NOT CORRODED.I TOOK IT OFF AND CLEANED IT UP ANYWAY,AND IT CAME BACK ON.BUT AS SOON AS I TURNED THE KEY OFF SHE WAS GONE AGAIN.I DONT HAVE ANY LIGHTS LIGHTING UP ON THE 4X4 SWITCHES.SERVICE 4X4 LIGHT IS ON IN THE DASH.DONT KNOW WHAT GOING ON.ANY SUGGESTIONS OR ADVISE GREATLY APPRECIATED.DUANE