Fault detecting method of vehicle

The present invention relates to a method of detecting a short circuit in a vehicle, capable of accurately detecting the short circuit of a high voltage component and a high voltage circuit in an electronic vehicle such as a hybrid vehicle including the high voltage component which is electrically insulated from the chassis of the vehicle. The method comprises a step of successively obtaining an insulation resistance sensing voltage value; a step of obtaining voltage change rates which are change rates according to the time of the insulation resistance sensing voltage value by successively calculating the change rates; a step of comparing the calculated voltage change rates with the predetermined value and of selecting a short circuit determination point when the voltage change rate is matched with a predetermined value; and a step of determining the existence of the short circuit using the insulation resistance sensing voltage value obtained in the short circuit determination point. [Reference numerals] (AA) Stray capacitance small and at fault; (BB) Stray capacitance small and at normal; (CC) Fault area; (DD) Accumulated threshold value; (EE) Normal area; (FF) Stray capacitance large and at fault; (GG) Stray capacitance large and at normal; (HH) Fault judgement; (II) Judgement point P1 (Stray capacitance small); (JJ) Variable control; (KK) Judgement point P2 (Stray capacitance large)