GM Service Manual Online
For 1990-2009 cars only

The battery load management feature is designed to monitor the vehicle's electrical load and determine when the battery is in a heavy discharge condition. During times of high electrical loading, the engine may idle at a higher revolutions per minute (rpm) setting than normal to make sure the battery charges. High electrical loads may occur when several of the following are on: headlamps, high beams, fog lamps, rear window defogger, the climate control fan at high speeds, heated seats and engine cooling fans.

If the battery continues to discharge, even with the engine idling at a higher rpm setting, some electrical loads will automatically be reduced. When this occurs, the rear window defogger may take slightly longer to clear the glass and the fan may cut back to a lower speed. For more battery saving information, see "Battery Saver Active Message" under DIC Warnings and Messages .