2006 GMC Yukon Owner's Manual - Page 355

Level Control {CAUTION: Shifting a four-wheel-drive vehicle's transfer case into NEUTRAL can cause your vehicle to roll even if the transmission is in PARK (P). You or others could be injured. Make sure the parking brake is firmly set before you shift the transfer case to NEUTRAL. 6. Shift the transfer case to NEUTRAL. See Four-Wheel Drive on page 2-26 for the proper procedure to select the NEUTRAL position for your vehicle. 7. Release the parking brake only after the vehicle being towed is firmly attached to the towing vehicle. 8. Turn the ignition off and lock the steering column. Automatic Level Control The automatic level control rear suspension is available on C/K 1500 vehicles and comes as a part of the Autoride® suspension, if equipped. This type of level control is fully automatic and will provide a better leveled riding position as well as better handling under a variety of passenger and loading conditions. An air compressor connected to the rear shocks will raise or lower the rear of the vehicle to maintain proper vehicle height. The system is activated when the ignition key is turned to RUN and will automatically adjust vehicle height thereafter. The system may exhaust (lower vehicle height) for up to ten minutes after the ignition key has been turned off. You may hear the air compressor operating when the height is being adjusted. If a self-equalizing hitch is being used, it is recommended to allow the shocks to inflate, thereby leveling the vehicle prior to adjusting the hitch. 4-59