2009 GMC Yukon Owner's Manual - Page 373

Level Control Automatic Level Control The automatic level control rear suspension is available on light-duty 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 ON/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 weight-distributing hitch is being used, it is recommended to allow the shocks to inflate, thereby leveling the vehicle prior to adjusting the hitch. Autoride® With this feature, improved vehicle ride and handling is provided under a variety of passenger and loading conditions. The system is fully automatic and uses a computer controller to continuously monitor vehicle speed, wheel to body position, lift/dive and steering position of the vehicle. The controller then sends signals to each shock absorber to independently adjust the damping level to provide the optimum vehicle ride. Autoride also interacts with the tow/haul mode that, when activated, will provide additional control of the shock absorbers. This additional control results in better ride and handling characteristics when the vehicle is loaded or towing a trailer. See "Tow/Haul Mode" under Towing a Trailer on page 4-52 for more information. 4-51