2004 GMC Yukon Owner's Manual - Page 309

The next time you start your vehicle, the TAS will not automatically come on. You can restore the automatic feature by using the same procedure. Whether the TAS is set to come on automatically or not, you can always turn the system on or off by pressing the TAS on/off button. Locking Rear Axle If your vehicle has this feature, your locking rear axle can give you additional traction on snow, mud, ice, sand or gravel. It works like a standard axle most of the time, but when one of the rear wheels has no traction and the other does, this feature will allow the wheel with traction to move the vehicle. Stabilitrak® System Your vehicle may be equipped with the Stabilitrak® system which combines antilock brake, traction and stability control systems and helps the driver maintain directional control of the vehicle in most driving conditions. When you first start your vehicle and begin to drive away, the system performs several diagnostic checks to ensure there are no problems. You may hear or feel the system working. This is normal and does not mean there is a problem with your vehicle. The system should initialize before the vehicle reaches 20 m.p.h. (32 km/h). In some cases, it may take approximately two miles of driving before the system initializes. If the system fails to turn on or activate, the STABILITY SYS DISABLED or SERVICE STABILITY message will be displayed. If the vehicle has gone through heavy acceleration or braking during the first two miles after starting your vehicle, the STABILITY SYS DISABLED message may appear. If this is the case, your vehicle does not need servicing. Turn your vehicle off and back on again to reset the system. If either message appears on the Driver Information Center (DIC), and your vehicle hasn't gone through hard acceleration or braking in the first two miles, your vehicle should be taken in for service. The STABILITY SYS ACTIVE message will appear on the Driver Information Center (DIC) only when the system is both on and activated. You may also feel or hear the system working; this is normal. For more information on the stability messages, see Driver Information Center (DIC) on page 3-56. 4-11