(4) According to the distribution of electrical components of each subsystem, confirm the wiring mode of connecting wiring harness, the electrical components connected by each connecting wiring harness and the direction on the car; Confirm the external maintenance mode and through hole maintenance of the wiring harness. Confirm fuse or circuit breaker according to electrical load; Color from the head; Check the type of terminals and sheathing that are connected to the wiring harness according to the adapter of the electrical equipment.