1998 bravada awd not working

any ideas to check , no fuses are blown, and no iddoit lights come on

How are you checking for not working?
Does the service 4W light come on and go off with key on bulb check?
Or come on engine running?

If there is a problem with it always check fluid level first.
A transfer case capable scanner is required to test it out and get transfer case codes.
Post back any codes.