My vacuum actuator is pulling in as soon as I start the truck. When I push the switch on the dash, I can hear it engage on the transfer case and the axle locks in and disengages when I push it again. What is making it pull in as soon as I start it, the vacuum switch on top of the transfer case or something else.

 

Could be a failed switch on the transfer case or it could be the vacuum lines being routed incorrectly. Search for "NV233+vacuum+diagram" and you should find the posts containing the schematics.