This page is all about how and why troubleshooting car problems should be approached in an organized and logical fashion. There is no good reason to just start guessing, or even educated guessing. Yes, I'm human just like you and continue to make this same mistake.
Many times when working on cars I get lazy and take an educated guess at what the problem might be. I know it's wrong, but I'll start diagnosing a system and see I have three choices of what the failure is. Instead of following the proper procedure of testing each individual component and continuing to diagnose the problem, I'll try taking a shortcut. This is known as the educated guess.
There's no good excuse for this, because the steps to get it right the first time are available in the service manual. All to often when I start guessing I fail to fix a car on the first attempt.
My educated guess will be wrong nearly 50% of the time or more. This means I have just increased my diagnosis time and replaced a car part that wasn't required and maybe non-refundable. I don't consider myself lucky. Even when it comes to a 50-50 chance I am wrong most of the time.
This brings me full circle and back to the professional method of troubleshooting car problems. Get a good auto repair manual and perform all the step-by-step diagnosis the service manual provides.
When you feel like the problem has been located, take the extra step and test the components. For example, if you believe the relay has failed. All relays can be tested and confirmed to be good or bad. Another example is if a switch has failed. An electrical switch is a simple device that can be tested and sometimes repaired. This will depend on the application.
In the two above examples, an automotive meter will be needed to test the individual electrical parts. A multimeter can measure voltage, amps, resistance and check for continuity.
Now a days automotive meters are inexpensive tools and a good thing to have in the toolbox. Good quality automotive style troubleshooting meters come with instructions on how to use them. Become familiar with these tools before you begin diagnosing car problems or replacing parts.
So to review the reason that we perform Diy car repair is to save money, learn something about the automobile we drive and reduce the overall downtime. Let's not ruin this by guessing at what parts we think might need to be replaced.
A resistance test can quickly find bad coils and automobile sensors. Another reason to have a multimeter on hand is that if your diagnostic steps in the service manuals require you to take a voltage reading, a test light should not be used in this situation.
If you are looking for a 5 V reference signal from the ECM, A test light will not be good enough. Also if measuring resistance is required only one tool can do this, yes an automotive meter.
Below are some
examples of multimeter tools that are inexpensive and can get the job
done. I own a fluke but this may be overkill for diy car repair. Note
the automotive technology book as well. This is what I use to study for
my ASE Electrical Certification tests!
Share this tips page with a friend having car problems.
Instead, let's properly diagnose and test the individual components we believe have failed. Take the extra time and you will save extra money as well as learn a valuable lesson about the proper procedure for troubleshooting car problems.
Another good website that covers do it yourself auto repair and has the cheapest professional printable electrical wiring diagrams for instant access is the Mitchell 1 website. To have deadly pinpoint diagnostic results you need the right tools.
I purchased the Mitchell powered car repair program for my own vehicle. I also made a video for you so you can see how this program works. This is no award winning film but the 4-minute demo does show you the key features of this online automotive repair manual.
Learn more about me and this automotive website on the about us page. This next link takes you to auto facts.org homepage.
I have supplied many more helpful articles for driveway mechanics. This next link takes you back to the homepage for DIY auto repair help.
I have 2 car repair websites. You can search both at the same time!