How do I disengage my 4 wheel drive in a 99 gmc jimmy?

A REAL PROBLEM WITH S-15 AND S-10 GM'S WERE THE VACUUM SWITCH ON THE TRANSFER CASE...WHEN THEY FAIL, THEY CASUE THE 4X4 TO STAY ENGAGED. THEY ARE THE SIZE OF A D-CELL BATTERY AND HAVE THREE VACUUM LINES RUNNING INTO THEM. THEY CAN ONLY BE PURCHASED FROM A DEALER FOR ABOUT $45.00. YOU DO NOT WANT TO REPLACE IT WITH A USED UNIT AS IT WILL FAIL AGAIN. IF YOU NEED A QUICK FIX UNTIL YOU GET THE SWICH AND REPLACE IT, REMOVE THE BATTERY AND BATTERY TRAY, THE VACUUM MOTOR FOR THE FRONT DIFFERENTIAL IS THERE. REMOVE THE 1/4 INCH VACUUM HOSE AND PLUG THE HISE. THIS WILL DISENGAGE YOUR 4X4 UNTIL YOU GET IT FIXED!

A SIMPLER QUICK TEMPORARY ANSWER, START BY SHIFTING INTO NEUTRAL WITH THE ENGINE OFF. THE VACUUM PUMP SHOULD NOT BE OPERATING. WHILE THE IGNITION SWITCH IS TURNED ON AND THE ENGINE IS OFF OR NOT RUNNING PRESS THE 2WD BUTTON. I FOUND THAT I DIDN'T HAVE TO TAKE ANYTHING APART TO GET IT TO SHIFT BACK INTO 2WD.

******This solution also works for the 1994 Jimmy as well! *******