2004 Chevrolet Silverado 1500 Pickup Owner's Manual - Page 205

Anti-Lock Brake System Warning Light With the anti-lock brake system, this light will come on when you start your engine and may stay on for several seconds. If the light stays on, or comes on when you're driving, your vehicle needs service. You will also hear a chime sound when the light is on steady. If the regular brake system warning light isn't on, you still have brakes, but you don't have anti-lock brakes. If the regular brake system warning light is also on you don't have anti-lock brakes and there's a problem with your regular brakes. In addition to both lights, you will also hear a chime sound on the first occurrence of a problem and each time the vehicle is shut off and then restarted. See Brake System Warning Light on page 3-44. That's normal. If the light doesn't come on then, have it fixed so it will be ready to warn you if there is a problem. 3-45