OK, I am not familiar with a 86, is the cruise built into the turn signal stalk ?  Did you look in the tech section in the 
manuals ?
     Also in the tech section are the 
wiring diagrams.  So here is a excerpt from the 81-87 instrument pg.1 showing the 
only place I found mentioned for cruise control.  Someone with more experience with a 86 model will have to chime in, but for now you can look through the manual and wiring diagram and familiarize yourself with them.  (see #4 and to the right of the words, bottom left corner is the number 4 on the buss bar).
