Circuit/System Description
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) monitors the state of charge (SOC) of the electrical system. If the BCM senses that the battery current was less than -2 amps and the SOC at key-on is 30 percent less than it was when the engine was last running, DTC B1527 00 will set.