POWER SOURCE SWITCH CONTROL DEVICE

A power source switch control device includes a detection circuit, a detection circuit, a detection circuit, and a detection circuit. The detection circuit detects forward voltage of a body diode of a FET, and the detection circuit detects forward voltage of a body diode of a FET. The detection circuit detects forward voltage of a body diode of a FET, and the detection circuit detects forward voltage of a body diode of a FET. A controller determines whether a defect of a power circuit has occurred based on results of the detection by the detection circuits to. Accordingly, the power source switch control device can appropriately detect defect of a switching element of a power source.