I removed the piece of trim that runs along underneath the passenger side door to under the glovebox, only to reveal two boxes with huge wiring harnesses hanging out of them , the lower one is black plastic, the upper one is larger and made of metal.

What are they for? I'd like to know before I go prodding around trying to run my new speaker wires from the doors!

The car is in my sig.

 

The black one is the keyless entry receiver. I don't know about the other one.

(info from Shoebox's Site )