Automotive Circuit Diagrams

Automotive Wiring Diagram Symbols

Normally Automotive Wiring Diagram Symbols refers to electrical schematic or circuits diagram. It uses simplified conventional symbols to visually represent electrical circuits and shows how components are connected with lines. Sometimes wiring diagram can also refer to the architectural wiring plan. It shows the locations and interconnections of outlets, lighting, electrical equipment and the wire routes based on a building plan. A good wiring diagram has to communicate information quickly, clearly, and with a low chance of misunderstanding.

automotive wiring diagram

Automotive Wiring Diagram Basic Symbols

Automotive electrical diagrams provide symbols that represent circuit component functions. For example, a few basic symbols common to electrical schematics are shown as:

  • (1) Switch,
  • (2) Battery,
  • (3) Resistor
  • (4) Ground.

Note the switch symbol displays an open or closed circuit path, which is what an actual switch performs. The battery symbol appears to be made of layers or plates, common to internal battery construction.

Automotive Wiring Basic Symbols 1

The resistor symbol appears to impede energy flow, which is a resistor function. The G100 ground symbol indicates a connection pointing downward (ground) that dissipates energy. The G100 designation is to help you find this location on the automobile.

Factory service manuals provide component location diagrams including important ground locations. Variations of symbols will exist depending on function or other characteristics. Examples are Variable Battery symbol:

  • (5) and the Case Ground symbol
  • (6) Electrical repair diagrams are mostly standardized for the above symbols.

Auto Wire Diagram Advanced Symbols

Abbreviated codes on the diagrams provide a circuit path and part or component information. They use the codes or labels to show circuit connector pin numbers, circuit values or component polarities.

These are standardized throughout the industry. Meaning, they’re the same abbreviated codes found in an Audi service manual or an American car reference book, like the downloadable Chrysler PDF manuals found here on

Auto Wire Diagram Advanced Symbols

All of these markings work together to add clarity to the diagnostic drawing. Here are a few label examples:

  • (1) A for Amperage or Amps.
  • (2) ORN for wire diameter and color
  • (3) 1340 for Circuit Path ID.

And here are another four notations you’ll find in factory service manuals

  • (4) P for pass-through grommet
  • (5) A for Pin ID & Location
  • (6) C1 for Terminal Connector ID
  • (7) B+ for battery positive.

Automotive Wiring Diagrams and Electrical Symbols

At first glance, the repair diagram may not convey how the wires use many colors and diameters. They show the diameter of each wire using a label placed at some point alongside its drawn line (1) (0.8). These can take some effort to locate on a fold-out map type diagram.

Nevertheless, being aware of the color of a wire remains important. (2) They provide wire color information as a color code label, in this case, black/white.

Automotive Wiring Diagrams and Electrical Symbols

(3) Also shown are common schematic illustrations of wires, (4) wires connected and (5) wires crossed but not connected. For consistency, most electrical schematics have signal or energy flow from top to bottom.

And component inputs on the left and outputs on the right. With that said, providing an understanding of how a system would function makes the wiring repair diagram one of the most valuable resources a technician can have.


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