The layout of electrical circuits and their components are shown as diagrams made up of symbols and connecting lines. Being able to read a circuit diagram is important when trying to trace and correct a fault in an electrical system.
Not all circuit diagrams use the same symbols or the same numbering system so refer to the manufacturer's service manual for specific details on how to read a particular circuit diagram.
This is a typical example of how a circuit diagram for a vehicle lighting system might be constructed.
 1. This is the park and tail light circuit. |
 2. To this circuit we add the circuit for the headlights and dipped lights. |
 3. Now we include the stop light circuit. |
4. Then we add the reversing light circuit. |
 5. And the indicator or turn signal circuits. |
 6. The completed circuit diagram represents all the wiring for the external lighting of a motor vehicle. Other circuits such as ignition, charging & starting circuits can be constructed in a similar way and added to provide a complete vehicle wiring system. |
