Speedometer works?
Check the connections.
Look for any chafing of the wires anywhere.
Go to the library and look up in the Motors or Chiltons manual about the cruise control. Most times they will let you make copies of the page(s) you need.
If it is still not working and everything seems OK, disconnect cruise cable from the throttle body and see if the cable pulls all the way out. I have had one that the cable broke at the servo. It's under the left fender.PITA