where exactly is the navigation door in the trunk?

Hi tmilano, I'm not sure what it is you're asking. Your Lexus either has the navigation system or it doesn't. If it does, then the navigation system is built into the center console and is updated through the CD/DVD player. Hope this helps!

Assuming you have the disk...........In the trunk in the back near the seats is a carpeted cover that covers the nav unit. At least that is where mine is in the 2006 SC 430.