The supply voltage is supplied to most consumers through the ignition switch. The power circuits of those electrical equipment components whose operation may be required under any circumstances are always connected to the battery, regardless of the position of the key in the ignition switch.
To connect the wires, electrical connectors with flat contacts are used.
For normal power supply to consumers, the electrical circuit must be closed, since otherwise there will be no electric current in it, for example, if a positive voltage is applied to the windshield wiper motor, it will not work until its electrical circuit is connected to ground. Switches, relays, fuses, measuring instruments, electric motors and other electrical consumers can be connected to an electrical circuit. To ensure proper connection of electricity consumers, the contacts of the electrical connectors are marked accordingly. To simplify the use of the electrical diagram, individual electrical circuits are arranged vertically and numbered. The bottom line in the diagram is the mass of the car. The connection to the vehicle ground is carried out either directly through the body of the electricity consumer or with an additional wire. Under the bottom ground line on electrical diagrams there are coordinates by which, using a key, you can determine an electrical circuit or element.
The numbers on the electrical diagram in the black boxes at the end of the wire indicate the coordinate at which it continues. There is also a backlink at this coordinate.
The color of the plug is indicated by a colored circle.
When working with an electrical circuit, you need to know the letter and graphic designation of electrical elements.