Gs4 connect to radio???

[therobman1]

Hello,


Im new to the galaxy and android platform. I have 2 cars both with different pioneer head units both have a usb connection, when i connect the micro usb all they do is charge the phone how do i make it play the audio out of the radio like my old iphone did. I have a mico usb card also and tried searching and found usb mass storage enabler and had no luck. I have a rooted gs4 att any help i would appreciate this is getting very frustrating

Thanks