To begin making a wiring diagram for a car, you first need to understand the different symbols that represent the function, power state, and location of the various components in the automotive electrical system. Some of the basic symbols common to wiring diagrams include switch and resistor. The symbol for switch is a straight line broken by another line that's drawn at an angle. A resistor is represented by a series of zigzag lines symbolizing current resistance.
There are plenty of other symbols that comprise an automotive wiring diagram, and the more complex the system, the more symbols are used. A few examples are antenna, ground, battery and fuse. Most symbols that appear on a wiring diagram look like abstract versions of the electrical components they represent.
After learning about symbols, the next thing to do is determine the purpose and function of your wiring diagram. If you need it to explain your car's electrical system to someone else, then you need to be accurate with every detail of your diagram, and you need to convey the information in an easily understandable manner. Following basic design and structure formulas can help make your diagram easier to read and understand.
You can make the process of making an automotive wiring diagram easier by using a diagramming software such as SmartDraw. SmartDraw comes with wiring diagram templates that you can customize by clicking on a symbol from the provided library and dropping it onto a line, after which the symbol automatically inserts itself into the diagram and snaps into place.