The ECU on the car is limited by the driving capacity, and generally cannot directly drive the high-power load. It only outputs the control signal, and controls the load operation through the relay in the power distribution box. Some ECUs come with PCB relays, which can directly drive the load, but generally without protection, the protection still needs to pass through the fuses in the power distribution box. The fuses and relays are passive components, there is no status monitoring and fault diagnosis, insurance power supply and The relay control is also open loop.