2007 Chevrolet Tahoe Owner's Manual - Page 249

Voltmeter Gage When your engine is not running, but the ignition is in RUN, this gage shows your battery's state of charge in DC volts. This condition is normal since the charging system is not able to provide full power at engine idle. As engine speeds are increased, this condition should correct itself as higher engine speeds allow the charging system to create full power. If there is a problem with the battery charging system, this light will come on or the SERVICE BATTERY CHARGING SYSTEM DIC message will display. See DIC Warnings and Messages on page 270 and Charging System Light on page 248 for more information. Brake System Warning Light When the engine is running, the gage shows the condition of the charging system. The charging system regulates voltage based on the state of the battery for improved fuel economy and battery life. The gage may transition from a higher to lower or a lower to higher reading, this is normal. Readings between the low and high warning zones indicate the normal operating range. Readings in the low warning zone may occur when a large number of electrical accessories are operating in the vehicle and the engine is left at an idle for an extended period. With the ignition on, the brake system warning light will come on when you set the parking brake. If you try to drive with the parking brake engaged, a chime will sound when the vehicle speed is greater than 5 mph (8 km/h). Your vehicle's hydraulic brake system is divided into two parts. If one part is not working, the other part can still work and stop you. For good braking, though, you need both parts working well. If the warning light comes on and a chime sounds there could be a brake problem. Have your brake system inspected right away. 249