There should be a vacuum switch on the brake pedal that releases vacuum when you push on the brake. Follow the vacuum hose out through the firewall to the diaphragm that controls the cruise and disconnect the hose there. Use a vacuum pump (or suck on the hose) to see if it holds vacuum. If not, your cruise will never come on, because it thinks the brake pedal is always being pushed. Mine had a rubber bumper on the brake pedal striker plate that rotted and fell out. I just taped a piece of wood there to replace the bumper, but it was a hack for sure.
...Just an idea of where to look, but it's an easy check. This was on my 94 Ranger with auto tranny, but it should be the same on the Explorer.
Also, years ago on my sisters 94 Explorer, (which is now mine), I had to replace an electronic box mounted above the glove box that controls the cruise. It was a big guess that the box was the problem, but it was cheap from the junk yard. It's still working.