The circuit requires only one relay and two diodes, and the relay completes the buzzer's operation. If the igniter is turned off and the vehicle light is still on, the contact of the long-closed relay is in a state of being connected in series with the coil of the relay. This means that the relay is disconnected every time it is energized. Therefore, the relay acts as a buzzer. 2D Barcode Module,2D Barcode Scanner Module,Rakinda Barcode Scanner,Arduino 2D Barcode Scanner Guangzhou Winson Information Technology Co., Ltd. , https://www.barcodescanner-2d.com