Figure 3-9.Single-line diagram.
What type of electrical diagram is used to identify the components of a system?
What type of diagram is used to find the location of a component?
What types of diagrams are the most convenient from which to learn the basic Functions of a
The schematic diagram shows, by means of graphic symbols, the electrical connections and
functions of a specific circuit arrangement. The schematic diagram is used to trace the circuit and its
functions without regard to the actual physical size, shape, or location of the component devices or parts.
The schematic diagram is the most useful of all the diagrams in learning overall system operation.
Figure 3-10 is a schematic diagram of an automobile electrical system. The automobile electrical
system uses the frame of the automobile as a conductor. The frame is called the ground side. Figure 3-10
shows all the electrical components grounded on one side. The negative side of the BATTERY is also
grounded. Therefore, the frame is the negative conductor of the system. The opposite side of each of the
components is connected through SWITCHes to the positive side of the battery. For the purpose of teaching
schematic reading, we will discuss only the lighting system and engine instruments.