GM Service Manual Online
For 1990-2009 cars only

First, turn your steering wheel left and right. That will clear the area around your front wheels. If you have a four-wheel-drive vehicle, shift into 4HI. Then shift back and forth between REVERSE (R) and a forward gear, spinning the wheels as little as possible. Release the accelerator pedal while you shift, and press lightly on the accelerator pedal when the transmission is in gear. By slowly spinning your wheels in the forward and reverse directions, you will cause a rocking motion that may free your vehicle. If that does not get you out after a few tries, you may need to be towed out. If you do need to be towed out, see Towing Your Vehicle .