I tested the 4WD while in the yard. When I was not moving and in neutral, I pushed the 4 High button, nothing happened and the light did not come on. I pushed the 4 Low button and I heard a sound below that I assume was the transfer case switching to 4 Low and the light came on. I pushed the Auto button and heard the same sounds (I assume from shifting back to high range) and that light came on. I pushed 4 High again and the light came on this time. I drove around some and I could tell it was in 4WD by the way it steered when I turned sharp. I switched in and out a few more times and everything seemed to work normally. So, maybe something was just sticking and freed up. The thing I'm not sure about is that the front wheel drive axles turn all the time, even when 4WD is not engaged. I'm referring to the shafts that have a boot on each end (which I assume is covering U-Joints) going to each front wheel. I know this because I had my wife drive real slow while in 2 High and I could see them turning. The front drive axles on my 1989 Suburban do not turn when it's in 2 High. It has a straight axle with automatic locking hubs.