1.CHECK GROUND CONNECTION
 
 2.CHECK KNOCK SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
 
 3.DETECT MALFUNCTIONING PART
 
 4.CHECK KNOCK SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
 
 5.DETECT MALFUNCTIONING PART
 
 6.CHECK KNOCK SENSOR
 
 7.CHECK INTERMITTENT INCIDENT