2002 GMC Envoy Owner's Manual - Page 96

Automatic Transfer Case (If Equipped) If your vehicle is equipped with the automatic transfer case, the transfer case knob is located to the right of the steering wheel on the instrument panel. Use this knob to shift into and out of four-wheel drive. You can choose among four driving settings: 2HI: This setting is for driving in most street and highway situations. Your front axle is not engaged in two-wheel drive. It also provides the best fuel economy. A4WD: This setting is ideal for use when road conditions are variable. When driving your vehicle in A4WD, the front axle is engaged, but the vehicle's power is sent to the rear wheels. When the vehicle senses a loss of traction, the system will automatically engage four-wheel drive. Driving in this mode results in slightly lower fuel economy than 2HI. 2-27