If you are paranoid you can pull the plug on the external key pad.

Thanks for all the help folks.

Perry

 

Hello Thanks for the information!

But in my 2006 F-350 there is a isolation in front of the box so I can't read the code! Now I bought this nice tool, because I can use it for my Harleys too. And I had found the code! I think in the U.S. you can buy tools like this too.
BATAVIA Videoskop mit 900 mm Schwanenhals bei eBay.de: Mess- Prüftechnik (endet 03.09.10 15:31:00 MESZ)

I hope this can help some people who search the code!

 

2005 Navigator. Just reset the personal code which was 11111 and retrieved my factory code as well. Underneath the right side kick panel tucked up and behind the wiring harness to the top left of the passenger fuse panel.