I've updated my iPhone 4S to iOS 6 and now I can no longer play music when connected to my car stereo via USB.
In the past, the stereo gave me the option to use either "Head Mode", where the function of the iPhone/iPod is controlled through the head unit, or "iPod Mode", where the device functions normally and just sends an audio signal through the USB cable to the stereo.
The "iPod Mode" is no longer available. According to the stereo's manual, it will only appear if the device supports it. Well, the device supported it until iOS 6.
Is this something that's changed in the new OS?