2003 GMC Sierra 1500 Pickup Owner's Manual - Page 196

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. That's normal. If the light doesn't come on then, have itfixed so it will be ready to warn you if there is a problem. Traction Off Light If you have the Traction Assist System, this light should come on briefly when you turn the ignition to RUN. If the light doesn't come on then, the system may require service; have it fixed so it will be there to warn you if the system is turned off. 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 car is shut off and then restarted. See Brake System Warning Light on page 3-40earlier in this section. If the light stays on, or comes on when you're driving, there may be a problem with your Traction Assist System and your vehicle may need service. When this light is on, the system will not limit wheel spin. Adjust your driving accordingly. 3-41