Playing music from I Tunes library in IPhone through car stereo
I have been playing music from my IPod Nano through my car's stereo system, using a wire with a plug on the end specifically meant to fit into the receptacle on the IPod. But when I connect my new IPhone 4s to the same plug, music comes out of the IPhone's little speakers, rather than my car speakers. What settings in my IPhone do I need to change to send the sound through my car's stereo system?