Traction Control light on from fresh start

fuse or dirty sensors

The traction control will reset when car is restarted even if the traction control button had been pressed.
Check the ESC fuse.
If you have been driving on really nasty wet streets, could be the wheel sensors have gotten dirty or a build up on them. Happened to me on the optima, and all it takes is one being dirty, or a snow buildup. I washed them off with a hose and everything was fine after that.
If that doesn't help take it in to a dealer

Right in by the back of the rotors, but I was wrong on the cadenza. The sensor is mounted inside a housing and senses off the axle at least in the front. Haven't checked the rear yet.
This is good means snow and ice will not effect the cadenza

Yooshaw
Yes the cadenza has speed sensors in the rear. They are facing toward the front of the car and on the back of the bearing housing. They are enclosed on the cadenza also.
These work the stability control.