2006 GMC (see signature) my wife drives it 90% of the time for errands. Quite a while ago (easily over a year ago) she had an incident and reported it was behaving as if it was in 4wd (she was on dry pavement, summer conditions etc.) while in the 2wd mode. I checked it out when she got back and could not repeat the issue. I noted it and that was it.
Today I was out running errands and as I swung wide into a parking stall, the drivetrain started bucking, the turn was clearly binding and the truck started behaving as if it was in 4wd on dry pavement again. I triple checked the buttons, 2wd was lit and I was sure I didn't nudge it while driving. I ran in to the store to complete the errand and came back out to deal with the problem. But it was gone. I cycled the transfer case through all the modes and then back to 2wd. Drove home and nothing was amiss.
96k (kms so about 60k miles) on the vehicle, the AutoTrak fluid was replaced at 80k (kms so 50k miles) with genuine GM AutoTrak. Truck is in mint condition and well maintained. This is my first "auto" t-case does anybody have any idea where to start looking for sensors etc. that might be commanding 4wd when I haven't pressed the button? Has anyone had this exact issue? I never use the auto feature, I don't like it and now it appears I am suffering with an option I didn't want / like anyway.
I will start with the obvious, checking grounds, connections etc.