OK... I'll put my 2? in here!
Back in April while in MOAB with the
Black Sheep Hummer Squadron 
every morning when I would go to 4lo lock the Service 4wd message would flash on the DIC. When I would try to go back to 4hi it would NOT go... the only way I could get it back into 4hi was to turn off the engine for at least 3-4 minutes, then after restarting there would be no message and I was able to go back to 4hi. This was really a pain in the A$$ especially trying to keep up with Sewie and Neo
and after the 3rd day it started to worry me. Sewie and all said it was probably a switch and not mechanical and sure enough... they were RIGHT!
Got the 3 into the GM dealer and the tech said it was a switch... mode switch I think he called it. He even said he got some codes out of it. Of course they don't have parts so I'll have to put up with it until they get parts. By then maybe I can get both the switch and the off-road light wind noise fixed! They are getting me a whole new off-road light bar since they botched up the first fix.
Thanks Sewie and all.... you were right! Just a switch... and still haven't got it or the lights fixed.
waitn on parts.
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Black Sheep Hummer Squadron
2006 H3 Superior Blue, Adventure + Lux Pkg, Automatic, Sunroof, GPS, Rocker Protection, Black Brush Guard, Roof-mounted off road lamps, Trailer package, Underbody Protection, ROLA Roof Rack, and now Toyo 35's!