Adding speaker to third row of SEL.

Hello CasaRod,

I assume the area your described is where a speaker would go.
As already pointed out that is the subwoofer. The speaker are in the window post rearward facing to the 3rd row occupants. I would check your sound setting to make sure the "fade" (balance) or direction of the music is not skewed, meaning it is not moved away from the back speaker and mainly playing from the front speakers. I would also make sure the feature where music ONLY plays in the front row is not enabled.

(taken from another post thanks to Gene...see below)
On page 2-13 of the navigation manual it says on the all menu screen touch Quiet mode
The audio volume will be muted.
NOW the part that might be causing your problem
" When the volume for the front seats is set to high, the volume decreases automatically."
Don't know if this is it but you can check easy enough.
Don't know why they would do that but it says it .

have no idea that it would be prewired for speaker.
Can't say I am personally annoyed by the lack of speaker there, as I do not sit in the 3rd row. I am the driver and have no need to be there.

I'd say take it to a local reputable stereo shop and have them quote you a speaker install if its that much of an issue for you. Be prepared as adding speakers with likely cause them to tell you you need an additional amp to drive them as OEM stereos have enough power to drive the OEM set up of speakers.