Schematic for vacuum switching valve

I own a '99 Trooper. My 4x4 will not engage as of 1 week ago. I think it lies in the vacuum valve actuator but I can't seem to trace where the vacuum lines go to. I can push the switch and the transmission instrument panel indicates that it is trying to engage but then gives me a check light. I have read many of the posts here but no one has mentioned where the vacuum hoses originate.

Any help or pointers would be greatly appreciated.

Wacle