2008 GMC Yukon Owner's Manual - Page 138

Shifting Into Four-Wheel Drive High or AUTO (Automatic Four-Wheel Drive) Turn the knob to the Four-Wheel High or AUTO position. This can be done at any speed, except when shifting from Four-Wheel Drive Low. The indicator light will flash while shifting. It will remain on when the shift is completed. Turn the knob to the Four-Wheel Drive Low position. You must wait for the Four-Wheel Drive Low indicator light to stop flashing and remain on before shifting your transmission in gear. Notice: Shifting the transmission into gear before the Four-Wheel Drive Low indicator light has stopped flashing could damage the transfer case. To help avoid damaging your vehicle, always wait for the Four-Wheel Drive Low indicator light to stop flashing before shifting the transmission into gear. The vehicle may have significant engagement noise and bump when shifting between Four-Wheel Drive Low and Four-Wheel Drive High ranges or from NEUTRAL while the engine is running. If the knob is turned to the Four-Wheel Drive Low position 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 less than 3 mph (5 km/h) and the transmission is in NEUTRAL (N). After 30 seconds the transfer case will shift to Four-Wheel Drive High mode. Shifting Into Two-Wheel Drive High Turn the knob to the Two-Wheel High position. This can be done at any speed, except when shifting from Four-Wheel Drive Low. See shifting out of Four-Wheel Drive Low later in this section for more information. Shifting Into Four-Wheel Drive Low When Four-Wheel Low is engaged, vehicle speed should be kept below 45 mph. Extended high-speed operation in 4L may damage or shorten the life of the drivetrain. To shift to the Four-Wheel Drive Low position, the ignition must be in ON/RUN and the vehicle must be stopped or moving less than 3 mph (5 km/h) with the transmission in NEUTRAL (N). The preferred method for shifting into Four-Wheel Drive Low is to have your vehicle moving 1 to 2 mph (1.6 to 3.2 km/h). 2-40