Vaccum Trouble +

I was wondering if someone had a diagram of the vaccum line including those that go down to the transfer case on a 1989 Jeep Cherokee. Also I would like to know if there's a way to test the electical part of the cruise control servo? I found at least in my jeep that one of the vaccum line off the servo runs over to a small blue switch that appers to me to be maybe a electric vaccum switch. Anyone else have any ides as to what it is?

Here you go:
http://www.autozone.com/images/cds/gif/large/0900823d80152533.gif