Cruise Control

I think the fuse box is at the left side of the dash, but I'm not sure. You need to check that the brake lights are not staying on or that you're not resting your left foot on the brake pedal. If the brake switch is activated, the cruise will cancel or not set. If you want to find a specialist, here's a directory link for you: https://repairpal.com/gmc-repair-in-marshfield-missouri