You can get all the technical information a Hyundai dealership tech gets at:
www.hmaservice.com
It's free for Hyundai owners. Very nice. Check there for any information regarding your cruise control you need.
RepairPal Certified shops can diagnose and repair your 2004 Hyundai Sonata. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.