In this paper, a power-on self-test scheme for buck-converter-based brushless DC motor drives is proposed to ensure the motor operating in safe operation area (SOA). At the beginning, the DC link capacitor between the buck converter and inverter will be charged. After that, it is used to provide current during inverter testing procedure. Generally, the faults are identified by detecting the maximum value of the discharging current. Based on the proposed fault-detection scheme, brushless DC motor can run safely by detecting the failures of inverter and three-phase windings of motor in advance. Compared with the traditional fault-detection schemes, only one current sensor with low accuracy is needed for proposed approach. In addition, potential components damage can be prevented since inverter is powered by capacitor instead of power supply. The feasibility of the proposed scheme is confirmed by simulation results.