Isolation Fault Protection
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 accessory AC/DC power control module contains a ground-fault circuit interrupter. If either the phase A circuit or the phase B circuit becomes shorted to the vehicle ground, or if the current on either circuit differs by greater than 6 mA, the accessory AC/DC power control module will turn OFF until the device is unplugged from the outlet and plugged into the outlet again.