2008 GMC Envoy Owner's Manual - Page 243

Let us say the road is wet and you are driving safely. Suddenly, an animal jumps out in front of you. You slam on the brakes and continue braking. Here is what happens with ABS: A computer senses that wheels are slowing down. If one of the wheels is about to stop rolling, the computer will separately work the brakes at each front wheel and at both rear wheels. ABS can change the brake pressure faster than any driver could. The computer is programmed to make the most of available tire and road conditions. This can help you steer around the obstacle while braking hard. As you brake, the computer keeps receiving updates on wheel speed and controls braking pressure accordingly. Remember: ABS does not change the time you need to get your foot up to the brake pedal or always decrease stopping distance. If you get too close to the vehicle in front of you, you will not have time to apply the brakes if that vehicle suddenly slows or stops. Always leave enough room up ahead to stop, even though you have ABS. Using ABS Do not pump the brakes. Just hold the brake pedal down firmly and let antilock work for you. You might feel the brakes vibrate or notice some noise, but this is normal. Braking in Emergencies With ABS, you can steer and brake at the same time. In many emergencies, steering can help you more than even the very best braking. 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. 4-5