Master Automotive Wiring Diagrams and Electrical Symbols

Common Electrical Symbols

Learning how to read a wiring diagram is like learning a new language. Here we’ll talk about what the common symbols stand for so you can take your auto repair game to the next level.

Watch the Diy automotive wiring diagrams video at the bottom of the page to find out how to use this information to pinpoint electrical problems like a pro. Don’t have time to soak up this much knowledge? Bookmark this page or share it with a friend.

My Name is Mark and I’m a Certified Master Technician. Wiring diagrams are drawings of electronic systems found in high quality workshop repair manuals. These diagrams are the quickest way to success when dealing with complex electrical problems on any vehicle.

On this page you’ll find in depth definitions for some of the most common symbols used in the industry standard line drawings. Understanding this visual language leads to faster detection of malfunctions and the capability to solve difficult car problems.

In the electrical schematics to follow you will see symbols are arranged in a circuit to reflect the function, power state, and relative location of various components.

An electrical symbol may have a slight resemblance to the actual component or its main function. It’s important to recognize when you see the solid and dotted lines on the diagram the difference between the two.

These lines actually represent current flow in and out of components connection points. The abbreviated text labels or codes placed next to the symbols and lines help you out further by providing descriptions or location information.

Automotive Wiring Basic Symbols

Common Symbols for Automotive Diagrams

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 and (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.

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

Auto Diagram Labeling System

Abbreviated codes on the diagrams provide 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, these are 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

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 Electrical Symbol

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 along side its drawn line (1) (0.8). These can take some effort to locate on fold out map style diagrams.

Being aware of the color of a wire is important.(2) Wire color information is provided as a color code label in this case black/white.

(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.

Component inputs on the left and outputs on the right. 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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These are about the same schematics in dealership manuals because they pull data from factory publications. You can print out what you need and take them right to the vehicle.

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More information on the use of automotive wiring diagrams. Take a look at 2 golden rules for using electrical troubleshooting manuals.

My latest video on my website has some advanced tips for using electrical diagrams to solve car problems. This is the method I use every time I break out a wiring diagram.

Find out more about me and this website. Also discover what gives me the right to talk about automotive wiring diagrams. This next link takes you to the homepage from this article about car wiring diagrams.