2004 Chevrolet Trailblazer drivetrain & axles problems

The failure involves the electro-mechanical device that shifts the car into four-wheel drive. The four-wheel is engaged by selecting 4wd with a dashboard selector switch. The switch will show a lighted indicator moving from 2wd to the 4wd. This indication is faulty. While driving towards a snow covered mountain road with several sharp turns going up the mountain the vehicles selector switch was moved to the 4wd position and the indicator light shown it was engage in the 4wd mode.

Purchased new trailblazer in may 04. When vehicle had approximately 3,000 miles on it, I started getting a rattle or loud buzz when accelerating at approximately 25 per hours just before the vehicle shifts. Occasionally, the shift if jerky. The vehicle has to be warm and the rattle or buzz first manifested itself after I turned right and accelerated from a stop. When warm, this sound is repeated almost every time I turn right and accelerate. When warm is also occurs when I just accelerate from a full stop.