Dirty

ive had a 5100nex for about 6 months now.I bought it from a friend and it was still new in the box.Ever since i installed it,the microphone will not work.Ive tried 3 different mics.It will not make any sound through my speakers(08 dodge ram 2500 with infinity).The person on the other end of the phone call can hear me but i cannot hear them.Anybody know what could be doing this?Also noticed that the gps will not come through my speakers unless i use the navigation on my iphone hooked to the usb