Actually, I THINK an FM tx IS the answer. BECAUSE: The only input I can find is a mono input for a phone adapter. You have your choice of the phone audio coming out of the left OR right speakers - and that appears to be about it.

Sure would be nice if one did. I found a page yesterday that shows MOST of the pinouts of the stock radio/nav. Only a mono phone input is shown.

I'v been hunting for that for at least two months and can't seem to dig it up.

I want to add an input, that is, to use the mono phone input to play a weather radio over the car speakers AND add the ability of making an FRS radio's speaker audio also play thru them the same way. (At my age, I have problems understainding peoplet thru those tiny FRS radio speakers.) It appears I MIGHT get this interface done this weekend, given what I found last night online. If so, I will post my results - but they won't help YOU as this will me a mono-input and will use the "Telephone" function of the radio/nav.

What YOU are attempting has been tried and discussed before, over and over, and it is my impression that you simply can't do it apart from using the old "FM transmitter" idea. Just my two cents - but research these pages yourself - don't trust me!!!!!!! I have a habit of missing stuff all the time.