Until just replacing the factory radio+nav (with a Sony XAV AX5000) I haven't needed to find the sub-woofer that's supposed to be installed with 7-channel Surround System. I know it's supposed to be under the driver's seat and see the wire connector in the lower right of the seat with wires going up/under the seat. Should I also be seeing the back side of the small speaker??? Actually, I can't recall ever feeling a rumble under the seat for the past 7-years. The Sony's sub-woofer feed is wired through an adapter to the factory plug which has a sub-woofer wire going into it. The Sony though doesn't seem to be recognizing there's a speaker so I'm tracing all the connections. Any thoughts any one? Thanks.