2003 GMC Sierra 1500 Pickup Owner's Manual - Page 290

Traction Assist System (TAS) Your vehicle may have a Traction Assist System (TAS) that limits wheel spin. This is especially useful in slippery road conditions. The system operates only if it senses that one or both of the rear wheels are spinning or beginning to lose traction. When this happens, the system reduces engine power to limit wheel spin. The traction control system is enabled every time your vehicle is started. The system will activate if it senses that any of the wheels are spinning or beginning to lose traction. You may hear or feel the system working or notice a lack of accelerator response, but this is normal. The Traction Assist System may operate on dry roads under some conditions. When this happens, you may notice a reduction in acceleration. This is normal and doesn't mean there's a problem with your vehicle. Examples of these conditions include a hard acceleration in a turn, an abrupt upshift or downshift 01 the transmission or driving on rough roads. If your vehicle is in cruise control when the TAS begins to limit wheel spin, the cruise control will automatically disengage. When road conditions allow you to safely use it again, you may re-engage the cruise control. See Cruise Control under Turn Signah"u1tifunction Lever on page3-7. n When the traction off light is on. the TAS is off and will not limit wheel spin. Adjust your driving accordingly. 4-9