omg, I had this problem on my front speaker on my '15 and I had to cut the wire back almost 6 inches, it was heavily corroded. Since I had to work on it, i went ahead and replaced all the speakers, front and back with a new jl audio unit set of speakers and i'll do the head unit later. Now my speakers sound great and not made of paper. Just in case, I forgot to check this forums, i kept taking another car AV forums but they never heard of this issue, i thought this would correlate with people going to get their speakers upgraded or checked but nope. I did all the upgrades myself, with instructions from crutchfield, I even called their tech support and they stayed on the phone and helped out while I connected the cables because I had to cut the toyota wiring due to the corrosion. They were extremely helpful and patient, highly recommended. This sucks, I only had the car 1 year before this happened. Anything else anyone knows I have to watch for? I heard the paint sucks too, which I assumed buying the car, but crap, I see chips everywhere. geez, anyway, yea these speakers and wiring are CRAP. lol.