You are not tied to the dealer like you are with GMs, BMWs, and VWs. Hyundai, Toyota, and Chrysler are the most customer-friendly manufacturers when it comes to making repairs parts and knowledge available to independent shops. All you need is a shop that regularly does brake work. They will have the equipment to read the fault codes and figure out where to start.
I can offer some generalizations as to the cause of the problem. If it's electrical in nature, like a broken wire to wheel speed sensor, that will usually not be intermittent, and it will be detected as soon as you start the engine. The fault code will be set and the warning light will turn on before you even start driving.
Problems with the computer or the hydraulic controller, both expensive parts, are typically not intermittent. That's not to say they never are intermittent, but most of the time those problems don't clear up at times and act up at other times.
One of the most common causes of the warning light turning on after driving for a few hundred feet to a many miles has to do with the signals coming from the wheel speed sensors. A signal could "drop out" meaning it's too small for the computer to read, or it could read the wrong wheel speed due to the tone ring being cracked. Dropouts can be caused by rust or metal filings building up on the magnet on the sensor's tip. That blocks a strong signal from being generated, and most often the dropout occurs at lower speeds when signal strength is naturally weaker anyway. On some cars rust can build up under the sensor and push it away from the tone ring. A larger air gap decreases signal strength.
A cracked tone ring is caused by water getting under it and expanding when it freezes. That results in a gap in the signal being generated.
Saturday, February 8th, 2014 AT 7:24 PM