Got it! It was the blue/white wire. System is running fine in 2004 M&T, a little low white noise can be heard at times, but I suppose that's expected.

So despite reading this, I'm still confused. Here's the low down.Got a Pioneer 3300UB for my M&T 2004 from Crutchfield, they send you all the goodies like harness and antenna adapter etc.Called them for assistance on what to solder where and was told to line up all the colors. Soldered, Taped, S...

Apologies for bumping this thread, but I didn't receive emails when new replies came and forget about it! Thanks for your hard work to figure out what the connector was for, but I'm curious could if this is indeed an input could I hack it into an AUX input for my 2004 M&T radio? Crazy, but I don...

I found this thing just dangling inside the right trunk compartment, have no clue what it's supposed to do.