2011 Chevrolet Avalanche Owner's Manual - Page 318

9-50 Driving and Operating Shifting Into Four-Wheel Drive High or AUTO (Automatic Four-Wheel Drive) Turn the knob to the Four-Wheel Drive High or AUTO position. This can be done at any speed. The indicator light will flash while shifting. It will remain on when the shift is completed. Shifting Into Two-Wheel Drive High Turn the knob to the Two-Wheel Drive High position. This can be done at any speed. The indicator light will flash while shifting. It will remain on when the shift is completed. Excessively shifting the transfer case into or out of the different modes may cause the transfer case to enter the shift protection mode. This will protect the transfer case from possible damage and will only allow the transfer case to respond to one shift per 10 seconds. The transfer case may stay in this mode for up to three minutes. Brakes Antilock Brake System (ABS) This vehicle has the Antilock Brake System (ABS), an advanced electronic braking system that helps prevent a braking skid. When the engine is started and the vehicle begins to drive away, ABS checks itself. A momentary motor or clicking noise might be heard while this test is going on, and it might even be noticed that the brake pedal moves a little. This is normal. If driving safely on a wet road and it becomes necessary to slam on the brakes and continue braking to avoid a sudden obstacle, a computer senses that the wheels are slowing down. If one of the wheels is about to stop rolling, the computer will separately work the brakes at each wheel. ABS can change the brake pressure to each wheel, as required, faster than any driver could. This can help the driver steer around the obstacle while braking hard. As the brakes are applied, the computer keeps receiving updates on wheel speed and controls braking pressure accordingly. If there is a problem with ABS, this warning light stays on. See Antilock Brake System (ABS) Warning Light on page 5‑22.