stayathomedad

I know this is a common problem I just don't want to start throwing parts at it. All buttons on the selector switch are on and seems to be working. It will engage in 4wd. I just bought it so I changed the front dif and transfer case fluid. Drive it around in 2wd and no problems, drive it in 4wd on prob but the light comes on later while in 2wd. Shifts in and out ok, no sounds or vibrations. So, transfer switch on the dash or the transfer case motor? Any suggestions?