2003 GMC Envoy Owner's Manual - Page 95

Four-wheel Drive If your vehicle has four-wheel drive, you can send your engine's driving power to all four wheels for extra traction. To get the most satisfaction out of four-wheel drive, you must be familiar with its operation. Read the part that follows before using four-wheel drive. You should use two-wheel drive high (2HI) for most normal driving conditions. 2HI (Two-Wheel High): 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. Notice: Driving in the 4-WHEEL HIGH (4HI) or 4-WHEEL LOW (4LO) positions for a long time on dry or wet pavement could shorten the life of your vehicle's drivetrain. A4WD (Automatic Four-wheel Drive): 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. 4HI (Four-wheel High): Use 4HI when you need extra traction, such as on snowy or icy roads or in most off-road situations. This setting also engages your front axle to help drive your vehicle. 4LO (Four-wheel Low): This setting also engages your front axle and delivers extra torque. You may never need 4LO. It sends maximum power to all four wheels. You might choose 4LO if you are driving off-road in deep sand, deep mud, and climbing or descending steep hills. Automatic Transfer Case 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. 2-26