I have a 08 Silverado that slips out of 4wd under load and then flashes "service 4wd" The drive shaft coming out of the front of the transfer case running to the front end isn't spinning at this time either. I don't believe it is an electrical problem but what are your opinions? Also until I cycle the key, the 4wd indicator wont allow it to switch back into 2wd.

Should I tear down the transfer case?

Thanks in advance

 

Yes. My guess would be one of the forks is worn and not able to make a fully apply/lock of the gear.