I recently experienced the situation in my 2011 Sonata GLS where the stability control system dashboard light came on (not blinking) and at the same time the cruise control would not set. Although I didn't realize it at the time, the brake lights had stopped working. My original new-car dealer diagnosed the problem as a failed brake light switch, which was replaced but only worked for half a day. A second dealer, who unlike the first could take my car again immediately, declared the new brake light switch to be defective and replaced it. It failed within three days. Finally the first dealer traced the problem to a wiring harness that had been (improperly) installed with a missing clip that eventually allowed a wire to be stripped by contact with a moving transmission part. After repair of this wire (two days ago) the second brake light switch is working correctly. Hope this is the end of the story!!