2007 GMC Yukon Owner's Manual - Page 148

Indicator lights in the button will come on to show which setting you are in. The indicator lights will come on briefly when you turn on the ignition and one will stay on. If the lights do not come on, you should take your vehicle to your dealer for service. An indicator light will flash while shifting the transfer case. It will remain on when the shift is complete. If for some reason the transfer case cannot make a requested shift, it will return to the last chosen setting. If the SERVICE 4 WHEEL DRIVE message stays on, you should take your vehicle to your dealer for service. See "SERVICE 4 WHEEL DRIVE message" under DIC Warnings and Messages on page 254. 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. Shifting Into Four-Wheel Drive Low To shift to the Four-Wheel Drive Low position, the ignition must be in 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 low is to have your vehicle moving 1 to 2 mph (1.6 to 3.2 km/h). 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 Low indicator light has stopped flashing could damage the transfer case. To help avoid damaging your vehicle, always wait for the Four-Wheel Low indicator light to stop flashing before shifting the transmission into gear. 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, and the indicator light will flash while shifting. It will remain on when the shift is completed. 148