Patent ID: 7877194

Claim:
A diagnosis method for a solenoid valve, wherein the solenoid valve includes a housing with a first and a second seat formed therein, a moving member configured to be moved in the housing, and a solenoid, and wherein the solenoid valve is configured to fully open with the moving member resting on the first seat when the solenoid is energized and fully close with the moving member resting on the second seat when the solenoid is deenergized, the diagnosis method comprising: cyclically energizing and deenergizing the solenoid of the solenoid valve to repeatedly fully open and fully close the solenoid valve; when the energizing and deenergizing causes collisions of the moving member against at least one of the first and second seats in the solenoid valve and noises are thus generated by the collisions, detecting occurrence intervals of the noises; and diagnosing whether the solenoid valve is in normal or abnormal condition based on the detected occurrence intervals of the noises, wherein the solenoid valve is diagnosed: as being in normal condition when each cycle of the energizing and deenergizing causes two noises; as being in semi-locked condition when each cycle of the energizing and deenergizing causes only one noise; and as being in fully-locked condition when there is no noise caused by the energizing and deenergizing.