Never really paid attention to it until now.
Pressed it and didnt really notice anything.
Its the button at the top of the driver side windows buttons. (above the one where you can move side mirrors)
Attatched a picture of what it looks like.

 

Your diagram is too small to read or to see the button clearly.

Do you have heated mirrors? Could it be a button for that?

I assume the button at the very bottom is to lock out the other windows other than the drivers side window? If the bottom button is not for that could that be the top button?

 

Yes the bottom button is to lock the windows. I'm going to go take a picture of it real quick and upload it. I don't think its heated mirrors also. i have the manual also but it shows nothing about this button. i was just at the dealership having its maintenance done and forgot to ask.

 

just added it...

 

Access height, drops vehicle by 40 mm for improved accessibility for passengers and luggage. PArt of the EAS system. Page 164 in owner manual for 2004, not sure of your year.

 

Thanks Savannah Buzz!
That ended up being what it was.