With the recent snowstorm we had I wanted to take my Tahoe out in the snow, first time with 4wd in weather like this. I started the truck, and put it into 4hi after I cleaned the snow off. However, there was no clunk or noise like it usually makes when switching to 4wd. And lo and behold, rear tires spun and the front tires did not move at all Truck hasn't thrown a service 4wd light or anything so far, I am thinking it is the transfer case actuator? Since that's what shifts the transfer case and makes the clunking noise I normally hear. Is there a way to diagnose the 4wd system that doesn't involve dealerships and big fees?