I guess this works for 2005 4th gen nav

http://www.clublexus.com/forums/showthread...66&page=1&pp=15

not 4 the GX though
srry

This worked on my 05 GX, but it doesn't save it. I held the Override button until it beeped, but still have to repeat everytime I shut off the power. No big deal since you can do it while driving. Thanks a lot for the tip, this used to drive my wife crazy!!!

Try these 2 both outline the same process of bypassing the speed sensor from reaching the head unit lock out and simulates the parking brake being held on.
http://us.lexusownersclub.com/forums/index...showtopic=24442
http://us.lexusownersclub.com/forums/index...?showtopic=6875

Does the '04 have an "override" button?? I'm not familiar with it.

bump for '04 solution

I have an 05 but I found this for your 04

Press on "Menu"

Press on "DVD"

Press on upper left corner of screen

Press on lower left corner of screen

Press on upper left corner of screen

Press on lower left corner of screen

Press on lower right corner of screen

Press on "Override" and hold until a beep is heard

Press "Back"

This resets each time the key is turned off.