Set corresponding insurance types for different load types and power types of electrical appliances. The electrical appliances are classified according to different load types, and the resistive load and the inductive load are used as insurance zones; the corresponding insurance type is selected according to the current type (steady-state current, inrush current).  It is necessary to separate the left and right light sources of the external lighting power supply and BCM lighting power supply to ensure the safety of the vehicle.  It should be ensured that all branch circuits under the same insurance are protected.  The relay model should be selected for different load types. There is a large inrush current when the load of lamps and motors is started, which will melt and stick the contacts of the relay, and there is a risk of failure. Therefore, it is necessary to determine whether a diode needs to be connected in parallel at the coil end of the relay according to the requirements of the control load.