My Ford expedition won't go into Four-wheel-drive?

I have a 2006 Ford expedition four-wheel-drive XLT it Will not go into four-wheel-drive I turn it on 4x4 high 4x4 low and will not do anything The lights on the dash don't light up for 4x4

Troubleshoot the 4x4 but i'm guessing it has a module and that module either doesn't have power or its toast.