98 s10 blazer 4wd problem
 

When I start the vec in the morning I can engadge the 4wd system in to all modes. After driving about 2 minutes the 4wd switch (3button) on dash flickers the 2wd and the 4wd lights back and forth quickly. Then after 15 mins of driving it stops flickering. 2wd light is life up and the 4wd sytem doesn't work when I press any buttons. I don't even hear the tccm or encoded motor when press the butons. I lolook at the tccm for corrosion none found. Wires and conector look good. Any help would be apreciated. Thanks