Car Schematic Electrical Symbols

Car schematic electrical symbols identify both components and how a system operates. We use automotive schematics as a road map to fix cars in a timely manor.

As you read through this page you can refer to the images as an example of basic automotive circuits. The pictures are labeled for your convenience.

With that said, take a minute to read and understand the surrounding text. I was fortunate enough to have some of the best automotive instructors in the business.

They helped me reach a deeper understanding of electrical circuits and I want the same for you. It will help you fix cars efficiently.

In this sites automotive electrical section you'll find two kinds of articles.

We've posted details about common electrical problems found in some of the most popular vehicles. As an example, how many times have you seen a Chevrolet truck with one daytime running light out?

When drivers attempt to replace the lamp they find much more than a blown bulb. In fact, they often find a melted electrical socket that needs repair in addition to replacing the 3157 bulb.

Basic Car Electrical CircuitBasic Car Electrical Circuit

If you're new to the site take a look at the article that walks you through strategy-based electrical diagnosis. The article helps you look at complex electrical problems in a simplified way.

Using the method outlined often locates the problem in the first few steps.

However, in order to read one of these wire diagrams you’ll need to understand what the car schematic electrical symbols stand for. And that's what this page is all about.

Wire Schematic Electrical Symbols

Car Schematic Electrical SymbolsCar Schematic Electrical Symbols

On the right, you'll see some of the most common car schematic electrical symbols used in professional wiring diagrams. Starting with the top left image, we see the symbol for the battery and just below it the symbol for ground.

Knowing the starting and ending point of the circuit goes a long way toward putting the circuit into perspective. Since the current flows from the positive to the negative, we can see how the electrical energy moves and powers this automotive system.

The next two images down represent the wires that connect all of the individual pieces of the circuit together.

You can see in the top image of the wires, in this example, the wires do not connect to each other. In the next image down you can see that the wires do connect to each other.

Whenever you have a wire to wire connection, it gives you a location to inspect. You check for two things.  Make sure this junction still exists and remains in good condition.

Take a good look at the circuit breaker and fuse image. If you have power coming from the battery and it's not reaching the switch or the load, it's time to check these devices.

Both of these things protect the circuit from overload. However, the circuit breaker either resets manually or automatically when the circuit malfunctions. On the other hand, the fuse melts and leaves a permanent open in the circuit to prevent damage.

The next car schematic electrical symbol I want to mention is the representation of the coil. Automotive wiring diagrams, use coils often. Whether they're located inside of relays and you can also see the coil in the solenoid symbol.

Basically, the coil energizes to activate a magnetic field. We use this magnetic field to close switches inside of a relay. It can also move a solenoid to perform a function. If this fascinates you learn more about the high energy coil used in an ignition system.

Ground Schematic Electrical Symbols

Car Schematic Ground SymbolsCar Schematic Ground Symbols

We use the ground schematic electrical symbol in every visual representation of a circuit. In order for the power to flow it needs to find its way back to ground.

As a mechanic I can tell you that ground problems occur frequently. Loose ground connections or one that suffers from corrosion build up can cause intermittent electrical problems .

Testing for a good ground is a quick and simple task all mechanics must learn. If you need a further explanation of this I made a YouTube video showing how to check electrical grounds.

In the image above you can see the upper symbol represents a case ground. This simply means that they decided to use the metal shell of the component to attach to a solid metal surface and supply a ground.

However, plastic parts can't use the case ground method. In this situation, they'll run a separate ground wire connection. Electrical schematics represent this single wire ground using the symbol in the middle of the image.

The Automotive Relay Electrical Symbol

Car Relay Electrical SymbolCar Relay Electrical Symbol

I wanted to include a simple automotive relay electrical symbol above. We'll talk about relays, because they are common in automotive circuits.

The relay includes several electrical symbols within the image itself. The symbols show this part is nothing more than a magnetically controlled switch.

Take a look on the right side of the image, you’ll see the coil symbol used. When they energize this it forms a magnetic field indicated by the dotted lines. At this point, with the field active, the switch moves position and completes the circuit.

Relating this to the real world of car repair, this means that you don't have to guess whether a relay is good or bad.

Check the terminals to verify the relay receives power. Next, verify the correct operation of the switch side of the relay. To drive my point home take a look at this page that focuses on a failed automotive air-conditioning relay.

I took close-up pictures with the cover removed so you can see exactly what I'm talking about. To find out what else this website covers you can visit the fix my old ride homepage or stop by and take a couple of our challenging automotive quizzes.

Author bio : Mark Gittelman is a retired ASE certified master technician, Chevrolet Professional Service Council member and the founder of FixMyOldRide.com. Watch the video on the about Mark Gittelman page to see his credentials, awards and certifications for yourself. Mr Gittelman hand writes all of the articles on FixMyOldRide.com unless indicated otherwise.