GMC 2010 Sierra - Manual (Page 242)

To use an accessory power outlet, remove the
protective cap. When not in use, always cover the
accessory power outlet with the protective cap.
Notice: Leaving electrical equipment plugged in for
an extended period of time while the vehicle is off
will drain the battery. Power is always supplied to
the outlets. Always unplug electrical equipment
when not in use and do not plug in equipment that
exceeds the maximum 20 ampere rating.
Certain power accessory plugs may not be compatible
to the accessory power outlet and could result in blown
vehicle or adapter fuses. If you experience a problem,
see your dealer for additional information on the
accessory power plugs.
The accessory power outlets are powered, even when
the ignition is in LOCK/OFF. Continuing to use power
outlets while the ignition is in LOCK/OFF may cause the
vehicle's battery to run down.
Notice: Adding any electrical equipment to the
vehicle can damage it or keep other components
from working as they should. The repairs would not
be covered by the vehicle warranty. Do not use
equipment exceeding maximum amperage rating of
20 amperes. Check with your dealer before adding
electrical equipment.
When adding electrical equipment, be sure to follow the
proper installation instructions included with the
equipment.
Notice: Improper use of the power outlet can cause
damage not covered by the vehicle warranty. Do not
hang any type of accessory or accessory bracket
from the plug because the power outlets are
designed for accessory power plugs only.
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