1998 GMC Envoy Owner's Manual - Page 87

Locking Rear Axle Your locking rear axle can give you additional traction on snow, mud, ice, sand or gravel. It works like a standard axle most of the time, but when one of the rear wheels has no traction and the other does,this feature will allow the wheel with traction to move the vehicle. Electronic Transfer Case The transfer case switches are above the radio controls. Four-wheel Drive Because your vehicle has four-wheel drive,you can send your engine's driving power to all four wheels for extra traction. To shift out of two-wheel drive andinto four-wheel drive, push the 4HI or 4LO button on the transfer case switch. You should use 2HI for most normal driving conditions. Use these switches to shift into and out of four-wheel drive. You can choose among three driving settings: Driving in the 4HI or 4LO positions for a long time on dry or wet pavement could shorten the life of your vehicle's drivetrain. 2HI: This setting is for driving in most street and highway situations. Your front axleis not engaged in two-wheel drive. 4HI: This setting engages your front axleto help drive your vehicle. Use 4HI when you need extra traction, such as on snowy or icy roads, or in most off-road situations. 2-26