I have a 2003 Tahoe with the service 4wd message. I had the code read today and it was c0306. I see that there are a couple of was to approach this from wiring to 4wd switch to control motor sensor. If anyone has had this code and knows where to really start I would appreciate the info.

Also, at the same time the service 4wd message appeared, I caught a smell of wire burning. Could this have been the switch or more possibly the harness somewhere?

 

At least you have communication with your transfer case computer. It's probably OK. When my actuator went out, the t-case would work in the "auto" setting only. You could hear it trying to engage 4-lo, but couldn't.