2007 GMC Savana Van Owner's Manual - Page 238

The StabiliTrak® system may also turn off automatically if it determines that a problem exists with the system. If the problem does not clear itself after restarting the vehicle, you should see your dealer for service. When this happens you may notice a reduction in acceleration, or may hear a noise or vibration. This is normal. Adding non-GM accessories can affect your vehicle's performance. See Accessories and Modifications on page 286 for more information. 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. If the brake-traction control system activates constantly or if the brakes have heated up due to high speed braking, the brake-traction control will be automatically disabled. The system will come back on after the brakes have cooled. This can take up to two minutes or longer depending on brake usage. The traction control system may activate on dry or rough roads or under conditions such as heavy acceleration while turning or abrupt upshifts/ downshifts of the transmission. All-Wheel Drive (AWD) System If your vehicle has all-wheel drive, your engine's driving power is sent to all four wheels for extra traction when needed. This is like four-wheel drive, but there is no separate lever or switch to engage or disengage the front axle. It is fully automatic, and adjusts itself as needed for road conditions. You may experience a brief vehicle vibration upon acceleration when driving in slippery conditions. This is normal and is an indication that the all-wheel drive system is functioning properly. 238