2009 GMC Savana Van Owner's Manual - Page 149

Voltmeter Gage When the engine is not running, but the ignition is on, this gage shows the battery's state of charge in DC volts. The vehicle can be only driven for a short time with the reading in either warning zone. If it must be driven, turn off all unnecessary accessories. Readings in either warning zone indicate a possible problem in the electrical system. Have the vehicle serviced as soon as possible. Brake System Warning Light The vehicle's hydraulic brake system is divided into two parts. If one part is not working, the other part can still work and stop the vehicle. For good braking, both need to work. When the engine is running, the gage shows the condition of the charging system. 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. 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 maximum power. If the warning light comes on, there could be a brake problem. Have the brake system inspected right away. United States Canada This light should come on briefly when ignition key is turned to ON/RUN. If it does not come on, have it fixed so it will be ready to warn if there is a problem. 3-31