Fault detection circuit, method and device

The invention provides a fault detection circuit, method and device. The fault detection circuit comprises N branch circuits, and the N is an integer larger than or equal to two; each branch circuit comprises a switch unit and a first resistance unit, wherein the switch unit and the first resistance unit are connected in series; each high-voltage assembly at least comprises one switch unit, wherein the two ends of the first branch circuit are connected with an input port/output port and the grounded end of a microcontroller respectively, and the first resistance unit of the ith branch circuit and the first resistance unit of the (i+1)th branch circuit are connected in parallel; the i is an integer larger than or equal to two and smaller than or equal to N. The fault detection circuit is used for judging the high-voltage assembly where an open circuit occurs through the current values of the input port/output port of the microcontroller.