2001 GMC Sierra 1500 Pickup Owner's Manual - Page 116

If your engine speed drops below 600 rpm, or if the engine is not running smoothly, you should downshift to the next lower gear. When operating on slippery surfaces, downshift at lower than normal vehicle speeds to prevent the tires from slipping. In bench seat equipped vehicles, move the tallest beverage containers to the right cupholder to provide additional clearance for the shift lever. For vehicles equipped with a center console, the front cup holder pulls out and turns 180_ to provide additional clearance between tall beverage containers and the shift lever. Shift Light If you have a manual transmission, you may have a SHIFT light. This light will show you when to shift to the next higher gear for best fuel economy. When this light comes on, you can shift to the next higher gear if weather, road and traffic conditions allow. For the best fuel economy, accelerate slowly and shift when the light comes on. While you accelerate, it is normal for the light to go on and off if you quickly change the position of the accelerator. If your vehicle has four-wheel drive and is equipped with a manual transmission, disregard the SHIFT light when the transfer case is in 4-Wheel Low. Ignore the SHIFT light when you downshift. 2-33