Transfer Case Motor or Dash Buttons? How do I tell which it is?

[Tahoe-boneau]

Good day... it appears my Transfer Case Motor has failed - twice in 5 years. How do I know it's not my switches on the dash? It all started a month ago as a growling in the front end that started at 60mph and got worse at 80, I've felt it in the steering. 4x4 has worked fine - the growling got worse, (I drive 75 - 80mph on interstate at least 100 miles a day) but only made noise at 60+mph. I had my tires rotated and balanced, no difference. Tires do not have cupping or uneven wear. I get the front end aligned monthly as I live on rough mountain roads and commute to work on the highway. A week ago I got a "Service 4WD" warning. Three days ago the dash buttons for the transfer case went out - all of them, even N and 2wd, my dash lit up with "stabilization off" and "go get your Tahoe fixed today" warnings. My dash buttons didn't do anything. No lights. At the same time my 4x4 quite working too, obviously - buttons didn't work anymore. (thank God I was in 2wd). As I said above, how do I know if it's the $250 rebuilt Transfer Case Motor, or the dash button cluster?... or something else. Oh, by the way, the growl appears to be a bearing on the passengers side drive shaft where it enters the housing. We hope that's it anyway... she's throwing lots of grease.

FYI... the 4x4 went out just a day after we came out of a 7 day freeze with temps dipping down to -20 below. I wonder if slush got stuck up there and got inside the unit, then froze. Perhaps it could ruin it? I hate to buy the wrong one. Once I install it, it's no takey-backies. Any advice? Many thanks for your help....

 

[YukonXL04]

If I remember right when the switch quit it was the same as yours, no lights. When the motor went I think the lights turned red or something...