Hi.
The message is referring to the Nav. System DVD located in the trunk. The problem is often caused by a defective DVD unit.
Try first disconnecting battery terminals for two minutes. Make sure that you have car stereo anti-theft code if needed.
If that does not help reach the DVD unit in the trunk, eject and load back the disk inside the player and check the data connection cable to the player.
Here a web page explaining how to reach the player. I quote:
"
Location
The DVD based navigation system is located in the trunk under the mat on
the passenger side of the vehicle. It is securely mounted under the
mat and deck. It is about the size and shape of a self enclosed
after-market radio. It sole purpose is to provide the Navigation
information for the vehicle.
STEP 1.[/b]
Remove the trunk mat completely from the vehicle and set aside. Lift
the decking using the handle exposing the spare tire. Completely remove
from the vehicle and set aside.
STEP 2
Remove the deck mounting tack using a small bladed screwdriver and lift
up. Set aside for replacement. Remove the side decking exposing the
DVD unit.
STEP 3
The DVD unit is mounted securely in place using 2 bolts on either side.
Both of these must be removed using an 8mm socket or a Philips
screwdriver. Set the aside for re-installation. (Be careful not to
drop them down into the cavities surrounding the unit. It looks dark
down there and you might not get them back)
STEP 4.[/b]
Carefully lift the front edge of the DVD unit up from its holder about 1".
DO NOT REMOVE THE UNIT COMPLETELY.
[b]
STEP 5
START THE VEHICLE. It must be running to provide power to the unit.
Remove the old DVD from the unit using the OPEN button by pushing in and
sliding to the left. This will reject the old DVD currently installed
in the unit. The Navigation screen will display a message indicating
there is not disk installed. Insert the new updated DVD into the slot
on the unit. Slide the OPEN button back to the right into its original
position. The navigation screen will display a message indicating the
system is loading the new data.
[b]
STEP 6
• Carefully push the unit back down in its mount. Replace the 2 bolts
• Replace the side deck and mounting tack
• Replace the spare tire deck and carpet mat."
If ejecting the disk does not do the job, before replacing the DVD unit you can try obtaining a replacement map disk from the Lexus dealer.
Regards.
Ginko