If its the front defrost, pull the controls out and make sure the cable moves when you put it to defrost setting. If its your rear defrost, unplug the tabs and take a multimeter to the terminals and check for continuity. If you don't have continuity, then your defrost lines are broken. check the compression/strut rod bushings and make sure they are not worn, and have a tire shop check the alignment on your front end because mine was off barely and did the same thing. For the 4wd light, its possible you just have a burnt out bulb.