2011 GMC Savana 3500 Passenger Owner's Manual - Page 169

Lighting A high electrical load occurs when several of the following are on, such as: headlamps, high beams, fog lamps, rear window defogger, climate control fan at high speed, heated seats, engine cooling fans, trailer loads, and loads plugged into accessory power outlets. EPM works to prevent excessive discharge of the battery. It does this by balancing the generator's output and the vehicle's electrical needs. It can increase engine idle speed to generate more power, whenever needed. It can temporarily reduce the power demands of some accessories. Normally, these actions occur in steps or levels, without being noticeable. In rare cases at the highest levels of corrective action, this action may be noticeable to the driver. If so, a Driver Information Center (DIC) message might be displayed, such as SERVICE BATTERY CHARGING SYSTEM. If this messages displays, it is recommended that the driver reduce the electrical loads as much as possible. See Battery Voltage and Charging Messages on page 5‑32. 6-7 Battery Power Protection This feature shuts off the dome lamps if they are left on for more than 10 minutes when the ignition is in LOCK/OFF. This helps to prevent the battery from running down.