1997 GMC Suburban Owner's Manual - Page 94

Locking RearAxle (If Equipped) If you have this feature, your 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, the locking feature will allow the wheel with traction to move the vehicle. I NOTICE: Driving in the4-WHEEL HIGH (4H) or 4-WHEEL LOW (4L) positions fora long time life on dry or wet pavement could shorten the of your vehicle's drivetrain. 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 2-WHEEL HIGH (2H) for most normal driving conditions. Front Axle Locking Feature The front axle locks and unlocks automatically when you shift the transfer case. Some delay for the axle to lock or unlock is normal. If the outside temperature is very hot, or the vehicle has been used under hard driving conditions, there may be a slight delay for the axle to unlock. 2-20