1996 GMC Yukon 4x4 Push-Button Selector Lights Are All On

What is your question?

Okay, so this is the third forum I've tried, so hopefully third time's the charm. My problem is this: My 1996 GMC Yukon 4x4 selector lights (push button) all come on, including the Neutral light (even when the vehicle is not in Neutral). I have checked the fuses, I even swapped the 4x4 fuse for good measure. The buttons do nothing when pressed (no change in lights, no sound from underneath the truck, etc., so I'm thinking that this may be an electrical issue rather than mechanical). Any help or at least a push in the right direction would be appreciated. I plan to turn this Yukon into a project mud/offroad truck, and obviously wouldn't get very far without 4x4!