2005 Cadillac STS Owner's Manual - Page 192

Charging System Light When you turn the engine on, this light will come on briefly to show that the generator and battery charging systems are working properly. If the warning light comes on, there is a brake problem. Have your brake system inspected right away. United States If this light stays on, your vehicle needs service. You should take your vehicle to the dealer at once. To save your battery until you get there, turn off all accessories. See DIC Controls and Displays on page 3-69 for more information. Canada This light should come on briefly when you turn the engine on. If it does not come on then, have it fixed so it will be ready to warn you if there is a problem. When the ignition is on, the brake system warning light will also come on when you set your parking brake. The light will stay on if your parking brake does not release fully. If it stays on after your parking brake is fully released, it means you have a brake problem. 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. 3-60