Sierra Classic 1500 4WD V8-5.3L (2007)
Auxiliary Power Outlet: Description and Operation
POWER OUTLETS DESCRIPTION AND OPERATION
The Auxiliary Power Outlet (APO) system provides up to 2,400 watts of 120-volt AC power. With these power outlets, you can plug in most auxiliary
electrical equipment and devices with a maximum limit of 2,400 watts. If you try to use equipment that requires more than the limit, a 20-amp
protection circuit will cut the power supply and a light in the APO switch will flash along with a Driver Information Center (DIC) message that will flash
120V OVERLOAD.
When running APO, do not have the front of the vehicle obstructed. Leave at least five feet (1.5 m) of space between the front of the vehicle and any
other object. This will allow airflow through the radiator and help to keep the SGCM cooler.
The power outlets are not designed for equipment with high initial peak starting power of greater than 2,400 watts, such as some air compressors, table
saws, etc.
Short Circuits, Overloads and Ground Fault Detection (GFD)
The 120-volt AC power outlets are protected against short circuits, overloads and ground faults. If the system detects a short or overloaded circuit, it
will immediately shut down the outlets and the light next to the APO button will flash, while at the same time a 120V OVERLOAD message will
appear in the Driver Information Center (DIC). After the fault condition is corrected, the system can be reset by pressing and releasing the APO
button. See "APO Operating Mode" for more information on the APO button. Short circuits may occur because a defective extension cord or defective
electrical device is plugged into an outlet.
Some electrical devices, such as motor-driven appliances and tools, have high start-up currents. During this start-up period, the 120-volt AC supply
will attempt to start the electrical device for up to 5 seconds. If the current does not fall below the maximum 20-amp rating of the APO within this
5-second timeframe, the system will shut down the outlets and the light next to the APO button will flash, while at the same time a 120V OVERLOAD
message in the DIC will appear. This type of situation is unlikely, but if it does happen, press the APO button and try to start the electrical device
again. If the electrical device fails to start a second time, it is probably because the device needs more start-up power than is available.
The Ground Fault Detection (GFD) system checks for leakage current to ground, or the truck frame, that could potentially be a shock hazard, in much
the same way as the Ground Fault Circuit Interrupt (GFCI) outlets protect you in your home. The GFD self-test is automatically performed during the
activation of the APO system. Thereafter, if the GFD system detects a significant leakage current, it will immediately shut down the outlets and the
light next to the APO button will flash, while at the same time a 120V GROUND FAULT message will appear in the DIC. If this happens, unplug all
electrical devices and reset the system by pressing the APO button. Then plug in each electrical device individually until the malfunctioning extension
cord or electrical device is identified.
If, after unplugging all electrical devices and cords and resetting the system, either the 120V OVERLOAD message or the 120V GROUND FAULT
message continues to be displayed, have the vehicle serviced.
APO Operating Modes
The APO system is capable of being operated in two different modes:
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Normal mode: This is used while the vehicle is running and in PARK (P), the vehicle is in Auto-Stop mode, or the vehicle is moving.
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Continuous mode: This is used while the vehicle is parked.
Normal Mode
This mode can be activated while in any transmission gear position to supply the outlets with 2,400 watts of 120-volt AC power.
To activate the normal mode do the following:
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Start engine
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Press the APO button once
If the system stops supplying 120-volt AC power unexpectedly and the APO button starts flashing, the system has detected an overload or ground fault
condition. To reset the system see "Resetting the Short Circuit, Overload or Ground Fault Detection (GFD) Circuit" later in this section.
The APO system will operate in the normal mode until you turn it off by doing one of the following:
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Pressing the APO button. The light in the APO button will turn off.
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Turning the ignition switch to ACCESSORY or LOCK.
Continuous Mode
This mode can be operated only when the vehicle is not moving and the transmission is in PARK (P) and will provide up to 2,400 watts of 120-volt
AC power to the outlets. Continuous mode can be operated with the key removed from the ignition. The engine will run continuously in this mode to
supply electrical power to the APO system.
To activate the continuous mode, do the following:
1. Place the transmission in PARK (P) with the ignition in RUN and the engine running. See "Ignition Positions" in your owner data Index.
2. Turn the ignition key to LOCK while the light is flashing. The light will flash for up to 30 seconds. When the ignition key has been turned to
LOCK, the light next to the APO switch will stop flashing and remain on. The engine will continue to run.
3. Connect any 120-volt AC electrical/electronic device(s) to the outlets. If you must use extension cords, be sure to use only UL(R) approved
