2009 GMC Sierra 1500 Crew Cab Owner's Manual - Page 227

This light comes on briefly when the ignition key is turned to ON/RUN. If it does not come on then, have it fixed so it is ready to warn if there is a problem. Antilock Brake System (ABS) Warning Light For vehicles with the Antilock Brake System (ABS), this light comes on briefly when the engine is started. { CAUTION: The brake system might not be working properly if the brake system warning light is on. Driving with the brake system warning light on can lead to a crash. If the light is still on after the vehicle has been pulled off the road and carefully stopped, have the vehicle towed for service. If the light comes on while driving, pull off the road and stop carefully. The pedal might be harder to push or might go closer to the floor. It can take longer to stop. If the light is still on, have the vehicle towed for service. See Towing Your Vehicle on page 4-47. If it does not, have the vehicle serviced by your dealer/retailer. If the system is working normally the indicator light then goes off. If the ABS light stays on, turn the ignition off. If the light comes on while driving, stop as soon as it is safely possible and turn the ignition off. Then start the engine again to reset the system. If the ABS light stays on, or comes on again while driving, the vehicle needs service. If the regular brake system warning light is not on, the vehicle still has brakes, but not antilock brakes. If the regular brake system warning light is also on, the vehicle does not have antilock brakes and there is a problem with the regular brakes. See Brake System Warning Light on page 3-42. For vehicles with a Driver Information Center (DIC), see DIC Warnings and Messages on page 3-66 for all brake related DIC messages. 3-43