4 Wheel Drive does nothin'........
 

Hey guys, this is my first post on this site. Any help or trouble shooting tips you can give me will be much appreciated. I have a 1999 S10 Blazer LT. I have the 4x4 switch on the dash that has 2HI, 4HI, 4LO and 4HI AUTO. The only position it will lock into is the 2HI. What steps do I take to determine where my problem is. Dash switch? Vacuum actuator under the battery compartment? Switch on the transfer case? or the TCCM?