4kq diff locks

[Rosso75@aol.com]

  I'm confused.  My diff's won't lock, but since I'm getting no vacuum at the
switch, I'm not surprised.  My cruise control is also out, but the door locks
work (they're all vacuum operated, right?).  I was checking fuses and they're
all good, but how is it there is no fuse for the door locks?  I can't find it
in the owners manual or on the fuse cover.  
  I'm assuming the vacuum for the diff locks goes to the switch, then to the
actuators on the center and rear diff.  Where does the vacuum supply line for
the switch come from?  I tried to follow it but would have had to take out the
dash and half the carpet to see where it goes. I've checked everything I can
find under the hood and all the lines seem to be good -- no split lines or
broken fittings.  Why does some of my vacuum operated stuff work, and other
stuff not?  Are there separate reservoirs?
Bryan Carter