1995 GMC Sonoma Owner's Manual - Page 104

You will see this light trash for a few seconds when you turn your ignition to RUN or START. Then the light should go out. This means the system is ready. If the air bag readiness light doesn't come on when you start your vehicle, or stays on, or comes on when you are driving,your air bag system may not work properly. Have your vehicle serviced right away. Brake System Warning Light Your vehicle's hydraulic brake system is divided into two parts. If one part isn't working, the other part can still work and stop you. For good braking, though, you need both parts working well. Your vehicle also has rear-wheel or four-wheel anti-lock brakes. See "Anti-Lock Brakes" in the Index. If the warning light comes on, there could be a brake problem with either your regular or rear-wheel anti-lock brakes, or both. Haveyour brake system inspected right away. This light should come on briefly as you start the vehicle. If it doesn't come on then, have it fixed so it will be ready to warn you if there's a problem. If the light comes on while you are driving,pull off the road and stop carefully. You may notice that the pedal is harder to push. Or, the pedal may go closer to the floor. It may take longer to stop.If the light is still on, have the vehicle towed for service. (See "Towing Your Vehicle" in the Tndex.) 2-58