Cruise Control

Recently while on the highway I thought I'd see if the cruise control worked, It doesn't. The buttons work I mean they depress, but what could be the problem and the fix? (88 GT)
Thx for advice.

Also my speedometer dosen't work I put in a new speedo gear figured that might have been the problem but it wasn't. Any ideas what else could be the cause?

check for a broken speedo cable . as far as the cruise it could be any number of things blown fuse , bad speed sensor, maybe one of the buttons are bad. Does your horn work? i think the cruise wires also go through the horn ring.

Thx for response. Where is the fuse box located on an 88 GT?