The fuel pump relay in the BYD F3 is located on the wiring harness assembly, not inside the fuse box. The wiring harness assembly is positioned below the steering wheel on the left side. There is a white box containing four relays, and the second relay from the left is the starter relay. The fuel pump relay controls the power supply to the fuel pump. In modern vehicles, which typically use direct or port fuel injection, the relay disconnects the fuel pump once the required fuel supply is achieved. The function of the fuel pump relay: A relay is an automated electrical switch that operates based on electromagnetic induction. The fuel pump circuit is usually equipped with an oil pressure relay, which serves to close its contacts when the required oil pressure is reached. This signal acts as an indication of normal oil pressure and is sent to CNC or PLC systems as a condition for enabling equipment startup. If the pressure falls below the required level, the relay contacts open, breaking the control circuit, triggering an alarm, and stopping the machinery to ensure personal and equipment safety. A relay is an electronic control device with a control system (input circuit) and a controlled system (output circuit). It is commonly used in automatic control circuits, functioning as an automatic switch that uses a small current to control a larger one. Thus, it plays roles in automatic regulation, safety protection, and circuit switching. The primary functions of the fuel pump relay include amplification, where a very small current can control a high-power circuit, and expanding the control range. When a signal reaches a certain value, the relay can simultaneously switch, disconnect, or connect multiple circuits based on the configuration of its contact groups, achieving the purpose of an automatic switch.
