I belive there is an electric motor/solinoid that engages the 4WD. Switch may be fine.
It could be something as simple as a bad fuse
No, Expedition's are all rear wheel drive.
yes
The 2013 Ford Expedition has rear wheel drive.
The 2007 Ford Expedition has rear wheel drive.
The 2006 Ford Expedition has rear wheel drive.
The 2011 Ford Expedition has rear wheel drive.
The 2002 Ford Expedition has rear wheel drive.
The 2009 Ford Expedition has rear wheel drive.
The 2008 Ford Expedition has rear wheel drive.
The 2001 Ford Expedition has rear wheel drive.
The 2010 Ford Expedition has rear wheel drive.