Try holding the brake pedal up with your foot when you hit "set". If that works, the brake light switch is out-of-adjustment.
Tug on the second throttle cable under the hood. It should pull up about half an inch at the throttle body assembly. If you get the whole thing in your hand, the cable is broken. That's not common. Check the vacuum hose going to the servo for cracks.
Additional tests are best done with a scanner that can display "inputs" and "outputs". It will show whether the various switches are working. There can also be fault codes stored related to the cruise control. Those codes don't cause the Check Engine light to turn on because they don't have an adverse effect on emissions.