Power control device and open-circuit fault diagnosis method thereof

An open-circuit diagnosis method for a power control device positioned between a power distribution device connected to output terminals of a first power supply and a second power supply and including a processor, the open-circuit diagnosis method comprising:

• determining, by the processor, a possibility of an open-circuit fault of a vehicle power source based on a current flowing through a power control switch that selectively connects or separates main power output from the first power supply and auxiliary power output from the second power supply;
• and
• determining, by the processor, whether it is possible to drive an electric load with an output power of the second power supply alone and determining an open-circuit position based on an output of the first power supply when there is the possibility of the open-circuit fault.