We don't have the manual for our GX, which we inherited from my in-laws. So, can anyone help me out? We have an '05 GX without nav, and when you put it in park only the driver's door unlocks. We want to set it up so that all the doors unlock. I remember it was something relatively simply to do in our Acura, but without the manual I'm not sure what to do. Any guidance would be greatly appreciated. Thanks!

It can be done by a Lexus dealer or repair shop with the appropriate handheld tester and program card: http://www.lexus.com/pdf/service/GX470_LPS.pdf

I've always thought it seemed kind of dangerous to have all any of the doors unlock automatically when the car is put into park.

You can register online lexus.com at https://secure.drivers.lexus.com/lexusdrivers/home
with your appropriate model year and the whole manual is available as search-able pdf format under vehicle resources. You can also request for a new paper manual but that's not necessary.