2007 Chevrolet Silverado 1500 Pickup Owner's Manual - Page 167

If the Four-Wheel Drive Low switch is pressed when your vehicle is in gear and/or moving, the Four-Wheel Drive Low indicator light will flash for 30 seconds and not complete the shift unless your vehicle is moving slower than 3 mph (5 km/h) and the transmission is in NEUTRAL (N). The transfer case will shift to Four-Wheel Drive High while waiting to complete the shift. It is normal to hear and feel your vehicle's transfer case shift into Four-Wheel Drive Low. If you shift with the vehicle stopped, the indicator light may continue to flash slowly. It may be necessary to shift the transmission momentarily into REVERSE (R) and DRIVE (D), for an automatic transmission, or REVERSE (R) and FIRST (1) for a manual transmission to make the light stop flashing. Shifting from Four-Wheel Drive Low to Four-Wheel Drive High or Two-Wheel Drive High To shift from Four-Wheel Drive Low to Four-Wheel Drive High or Two-Wheel Drive High, your vehicle must be stopped or moving less than 3 mph (5 km/h) with the transmission in NEUTRAL (N) for an automatic transmission or the clutch pedal pressed for a manual transmission. The preferred method for shifting out of Four-Wheel Drive Low is to have your vehicle moving 3 mph (5 km/h). Press and release the Two-Wheel Drive High or Four-Wheel Drive High switch. You must wait for the Two-Wheel Drive High or Four-Wheel Drive High indicator light to stop flashing and stay on before shifting the transmission into gear or releasing the clutch pedal. If the Four-Wheel Drive High switch is pressed when your vehicle is in gear, the Four-Wheel Drive High indicator light will flash for 30 seconds but the vehicle will not complete the shift unless it is moving slower than 3 mph (5 km/h) and the transmission is in NEUTRAL (N). 167