2009 Tahoe 4wd will not engage

[Kody]

I have 2009 Tahoe LTZ and am having issues with 4wd. When I switch it into Auto 4wd the light flashes for a long time. Sometimes it will eventually go into Auto, other times will not and the service 4wd message will show up on the dash. However, even if I can get it into 4wd, the front wheels still aren’t engaging. I’m not exactly sure how the system works, but I believe an electric motor shifts the transfer case into 4wd and starts turning the front drive shaft and in addition there is an electric actuator that then engages the front differential. Based on my symptoms I may be having issues with both. Looking for some additional info on how the systems works and what things I can check/replace myself before I take it into the dealer. I did some searching but couldn’t find specifics, links to any related threads are appreciated as well

Thanks

[efritz]

You must have a scanner that can read C codes to get a proper diagnosis. Some Autozones/Oreilly's have them, but if you have under 100k, just take it to the dealer as you still have a powertrain warranty. Very likely an encoder motor or front actuator, but don't even mess with it if you have warranty, just take it in...

[SILVERADOSC540]

Are you over 100,000 miles? Should be a warranty issue.

[Kody]

Actually i only have 60k, didn't buy it new, just completley forgot it was under warranty