2005 GMC Envoy Owner's Manual - Page 305

Whatever the condition - smooth ice, packed, blowing, or loose snow - drive with caution. If you have the traction assist system (TAS), it will improve your ability to accelerate when driving on a slippery road. But you can turn the TAS off if you ever need to. You should turn the TAS off if your vehicle ever gets stuck in sand, mud, ice, or snow. See If Your Vehicle is Stuck in Sand, Mud, Ice or Snow on page 4-42. Even though your vehicle has TAS, you will want to slow down and adjust your driving to the road conditions. Under certain conditions, you may want to turn the TAS off, such as when driving through deep snow and loose gravel, to help maintain vehicle motion at lower speeds. See Traction Assist System (TAS) on page 4-8. If you do not have TAS, accelerate gently. Try not to break the fragile traction. If you accelerate too fast, the drive wheels will spin and polish the surface under the tires even more. What is the worst time for this? Wet ice. Very cold snow or ice can be slick and hard to drive on. But wet ice can be even more trouble because it may offer the least traction of all. You can get wet ice when it is about freezing, 32°F (0°C), and freezing rain begins to fall. Try to avoid driving on wet ice until salt and sand crews can get there. 4-39