Car wiring diagrams sometimes referred to as schematics are used to show how circuits are constructed. A typical service manual will contain dozens of these schematics that can help with proper diagnosis and repair.
On this page is a how to video some coworkers and I put together. It explains how to find specific automobile wiring diagrams, but more importantly tips on using them to solve most electrical car problems you will come across! This video is good stuff and worth 4 minutes of time.
I share with you the method I've been using for 27 years. It is fast, efficient and often locates the problem on the first step. The video has had over a half a Million views and just a couple thumbs down. You can't please everybody but I tried.
One guy was upset that I mentioned using a test light instead of a meter. Although there is no question that a meter is more accurate and better for diagnosis I still own and use a test light for quick checks. But lets get back to the diagram issues.
First let me tell you what a wiring diagram will not do. Automotive wire diagrams do not show the actual position of parts or physical appearance. Standard wire diagrams don't reveal the length of conductor that runs between the particular components shown.
There are electrical symbols posted on the schematics that will indicate the color of the wire, its thickness or size and other important details about that particular circuit such as connector locations.
Identifying the color of the wire is important for accurate
diagnosis. If you test the wrong wire you will go down the wrong branch of the tree chart. The standard labeling system will use the first letter to
indicate the base color, and the second letter to indicate the stripe
color. An example would be the letters OB. This would be an orange
colored wire with a black tracer stripe. RB is red with a black tracer.
Wire repair diagrams can become quite complex. To avoid this, most troubleshooting manuals will illustrate only one distinct system or circuit at a time. A horn circuit or turn signal circuit each have a separate distinct electrical schematic.
Keep in mind that electrical symbols are not always standardized throughout the automotive industry. Different manufacturers may have different methods of representing certain components particularly the less common ones. Always refer to the symbol reference charts. These are listed in the beginning of the electrical section in most manuals.
In this video I share the method my electrical instructor taught me. He was an evil genius and his brain flowed like electrons. Most auto mechanics have learned a different method. I think, what is more important is to use a standard procedure and follow it religiously for each electric diagnosis. Sticking to a routine helps you find problems faster.
Bookmark this resource page or share with a friend. Come back and watch the video again if you get stuck!
Find 3 more instructional videos about how to use online auto service manuals to fix cars right the first time. This next link takes you to my page about online factory auto repair guides.
Do you require one on one help with your particular electrical problems? On this website automobile repair help is always available for you.
Testing individual electronic components is not only a valuable skill
but a big part of fixing electrical problems on cars. In my college
training classes we sat down with bread boards and learned how to
diagnose and repair individual components. The video on the right has the same goals.
You learn about the tools and the proper equipment required for automotive electrical tasks but more importantly how to decipher the test results. In addition It includes how to check voltage, resistance, amperage and good stuff about Ohm's Law.
In my opinion it is a clear and concise video with enough attention to detail so the enthusiast understands what this stuff means to the efficient repair of automotive electrical circuits. Yes it's a little weak on the animations and voice over but If you have an interest in electronics and are a beginner or a seasoned professional looking to sharpen some skills I think you will benefit from watching it.
Find out what else is available on this auto repair website on the Homepage for YouFixCars.com. You can also learn more about the car mechanic that created this information portal.