2008 GMC Yukon Owner's Manual - Page 309

Antilock Brake System (ABS) Your vehicle has the Antilock Brake System (ABS), an advanced electronic braking system that will help prevent a braking skid. When you start the engine and begin to drive away, ABS will check itself. You might hear a momentary motor or clicking noise while this test is going on. This is normal. If there is a problem with ABS, this warning light will stay on. See Antilock Brake System Warning Light on page 3-46. 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. Along with ABS, your vehicle has a Dynamic Rear Proportioning (DRP) system. If there is a DRP problem, both the brake and ABS warning lights come on accompanied by a 10-second chime. The lights and chime will come on each time the ignition is turned on until the problem is repaired. See your dealer/retailer for service. 4-5