I think the windshield (the checkerboard black by the rear view). I could be wrong.

 

I've been having trouble with my GPS dropping satellites (2016 iGrand Touring), so after a lot of trial and error I'm pretty sure it's the antenna part (which might also include a chip). Anyway, I located it - you have to pry open the center speaker grill with a thin wedge (like a putty knife). Comes out easily. You will see the center speaker and to the left is a small metal box with a black wire. One screw holds the antenna box in place and the wire has a connection plug to disconnect the wire that ultimately goes to the infotainment unit. The part is about $50 to replace (doesn't come with cable to infortainment unit). Looks like you can disconnect the old one and plug in the new one.