Short Circuits, Overloads and Ground Fault Detection (GFD)

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

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 time frame, 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.