When I installed my Pioneer Avic D3 with the Bose system, I had a total dumb attack...had no sound. I did everything right, it was late, I pulled the head unit a few times to go over everything again, browsed the web to figure it out...you name it.
I forgot to connect the speaker wires.
Wasn't a simple plug and play and I had the module for the steering wheel control, the factory connections....but I still needed to seperately connect all 8 speaker ( +&-) leads.
I can't count how many stereos I've installed in my day, can't believe I overlooked this.