Does the actuator get vacuum in 2wheel or 4wheel? Mine is pulling in when in2wheel.

 

It's supposed to only get it in 4.

 

You either have a bad vac switch on the t_case or somebody has the hoses swapped around.

 

When I bought My JIMMY in '07, the 4X4 didn't engage so I searched & found that the vacuum line cluster on top of the trans/tc was not put on in the right spot. There is a small hole in the rubber vacuum cluster that lines up & goes onto that connection, that "connection" has a long skinny plastic stem that the vacuum line cluster slips over. Hope that helps & your problem is that simple too! BTW, it is very hard to see what You are looking @ up in there. It is best done on a rack!