We use car schematic electrical symbols to identify both components and how a system operates. We use automotive schematics as a road map to take us to a repaired car. As you read through this page you can refer to the image on the right as a basic automotive circuit.
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. In addition to these articles covering specific repairs we started adding educational content to help do-it-yourself mechanics diagnose electrical problems.
If you're new to the site take a look at the article that walks you through strategy-based electrical diagnosis. In a nutshell, that article helps you look at complex electrical problems in a simplified way.
More importantly, it puts you in the routine of proceeding in a manner that 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.
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 through and powers this specific 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. I'm not going to hit on every single one of these individual electrical symbols. With that said, 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 briefly is the representation of the coil. Automotive wiring diagrams, use coils often. Whether they're located inside of relays or you can see the coil in the representation of 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.
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.
Applying some real life experience as a mechanic I can tell you that ground problems occur frequently. Whether it's a loose ground connection or one that suffers from corrosion build up between the connector and the metal surface, these areas require careful inspection.
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. However, I wanted to point out what the car schematic electrical symbols look like for the two different types of grounds you'll find in an automotive circuit.
In the image to the right you can see that 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.
Nevertheless, in many situations the components made from plastic or the location doesn't allow a case ground. In this situation they will run a separate ground wire that attaches directly to a solid metal surface. We represent this single wire ground using the car schematic electrical symbol in the middle of the image.
I wanted to include a simple automotive relay electrical symbol, supplied here on the right. I wanted to stop and talk about this individual component, because it's extremely common in automotive circuits.
Another interesting thing about these devices is it includes several electrical symbols within the image itself. The car schematic electrical symbol shows this relay 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.
You can check the terminals to verify the relay receives power. You can also 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 automotive air-conditioning relay that failed.
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.