Although vehicles use various types of brake systems and different technologies, themain purpose is to ensure safe navigation of vehicles in traffic, slow down and stopthem. Air brake systems are used in heavy vehicle vehicles carrying loads and passengers. In case of any air leakage that may occur in the braking system during the courseof the cruise, a part called The Four-Way safety valve is used to prevent the air tanksfrom emptying completely. The task of the four-way safety valve is to ensure that compressed air to be used for the handbrake, front axle and rear axle is stored in separate airtanks. In the event of a possible air leak, the damaged tank should not affect the tanksthat are intact. During periodic controls of vehicles, air brake system is tested for fourway safety valve. In the current case, the four-way safety valve test is conducted manually. In this study, the four-way safety valve test was intended to be performed automatically. For this purpose a tester was developed using microcontroller card, solenoidvalve, pressure transmitter and PC software. Thanks to the developed Tester and software, the test is automated and the non-ergonomic movements made by the technicianare eliminated. The reliability of the test has been improved and the polluting elementshave been eliminated during the test.