2006 GMC Yukon Owner's Manual - Page 306

When the StabiliTrak® system has been turned off, you may still hear system noises as a result of the brake-traction control coming on. It is recommended to leave the system on for normal driving conditions, but it may be necessary to turn the system off if your vehicle is stuck in sand, mud, ice or snow, and you want to "rock" your vehicle to attempt to free it. It may also be necessary to turn off the system when driving in extreme off-road conditions where high wheel spin is required. See If Your Vehicle is Stuck in Sand, Mud, Ice or Snow on page 4-44. When the transfer case is in 4LO, the stability system is automatically disabled, and the STABILITY SYS DISABLED message will appear on the DIC. In 4LO, the StabiliTrak® button only turns the traction control system on and off. The traction control system is enabled automatically when you start your vehicle, and it will activate and display the TRACTION ACTIVE message in the Driver Information Center (DIC) if it senses that any of the wheels are spinning or beginning to lose traction while driving. If you turn off StabiliTrak®, only the brake-traction control portion of traction control will work. The engine speed management will be disabled. In this state, engine power is not reduced automatically and the driven wheels can spin more freely. This can cause the brake-traction control to activate constantly. For more information on the traction active message, see Driver Information Center (DIC) on page 3-52. Notice: If the traction off light comes on due to heavy braking and/or because the traction control system has been continuously active, do not allow the wheel(s) of one axle to spin excessively. If you do, you may be causing damage to the transfer case. This could lead to costly repairs not covered by your warranty. If the brake traction-control system activates constantly or if the brakes have heated up due to high speed braking, brake traction-control will be disabled and the TRACTION SYS LIMITED message will be displayed. Traction Control Operation The traction control system is part of the StabiliTrak® system. Traction control limits wheel spin by reducing engine power to the wheels (engine speed management) and by applying brakes to each individual wheel (brake-traction control) as necessary. 4-10