Why does your car make a moaning noise when turning?

Check your power steering fluid.
If your car has Versatrak all wheel drive, it probably the transfer case and rear differential. Changing the fluid will correct the problem. Make sure you use General Motors Versatrak Fluid only, nothing else is approved for these units!! It's expensive but it will correct the problem. You will need 4 bottles of fluid (2 liters). The transfer case is directly behind the transmission, simply drain and refill it and the rear diff after driving a few miles to warm them up. Take the car to a parking lot and make four or five figure 8's to get the new fluid into the clutch packs. The moaning should be better, but it may take about 500 miles of driving to completely eliminate it.
If that doesnt do the trick then its probably the belt. Especially during winter they get dried out or tighten up and crack so replacing it should stop the noise. Be easy on turns you dont wanna bust a cv (constant velocity) joint and it strains the belt the harder you turn.