3 Must Have Electronic Testing Tools for Home Auto Mechanics

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Right ToolBefore you get nervous, allow me to explain. While there are many times that your vehicle requires professional attention, there are also instances when you can save time and money by performing an elementary repair for yourself. Have you ever taken your car into the shop for a “service engine soon” (SES) indicator light only to discover that it was triggered by a fuel cap error? If you had owned a few basic electronic testing tools, then you could have saved time, money, and inconvenience, by repairing the condition for yourself.

Maybe you perform all of your own automotive repairs, but stop short of electronic malfunctions. Does this sound anything like you? Stop being intimidated by modern technology, buy a few inexpensive tools and save yourself some dough. Just follow the tool manufacturer’s directions carefully.


Code Reader

code reader
Equus Code Reader

Vehicles manufactured after 1996 are equipped with an On-Board Diagnostic system called an OBD-II. While vehicle scanners are necessary for professional automotive repair facilities to communicate with OBD-II systems, they can be extremely expensive and not practical for home auto mechanics to purchase. What I recommend is an inexpensive code-reader. Companies like Equus and Actron offer reliable code readers which are relatively inexpensive (under $100) and simple to use. If you can “point and click” then you can operate the code reader. Once the code is obtained, you can organize your plan of attack. Trouble code flow charts are available online; start searching in images and chances are that you will find that for which you are looking. For instance, if an evaporative emissions code, indicating that the fuel cap was not tightened properly, was retrieved by the code reader, the solution is simple. Tighten the fuel cap and clear the code, then drive the car and see if the SES lamp resets. If it does not, then you just paid for your code reader. If you obtain a code which you do not feel comfortable attempting to repair, at least you will have an idea of what to expect when you turn your car over to the professional repair shop.


  • Code readers are inexpensive and have a long life span.
  • You can reset simple codes, such as fuel cap related codes, without paying diagnostic charges.
  • Code readers are easy to use.


  • Don’t be duped into replacing expensive components simply because they are described in the trouble code. A thorough diagnosis must be reached before replacing parts.

Digital Volt and Ohm Meter (DVOM)


After a trouble code is obtained, a DVOM will be required for an accurate diagnosis. Following wiring schematics, connector views, and diagnostic flow charts (downloaded from the internet) you will use the DVOM to test for the presence of battery voltage, vehicle ground signals, and sensor data (as well as circuit resistance) at various points to determine the integrity of electrical components, wiring harnesses, and electrical connections. With these determinations you will follow the flow chart to an accurate diagnosis, replace the faulty components, and save a bundle of cash.


Circuit Testers

test light 1
Test Light

Also referred to as a test light, the circuit tester is a simple device which indicates whether or not a particular electrical circuit is complete. This type of tester is helpful in locating blown fuses, as well as determining if a battery voltage or ground signal is being supplied to an electrical component. They are sold as powered and unpowered circuit testers.

  • An unpowered circuit tester requires voltage from the vehicle to illuminate a bulb which is integrated into the handle of the device. One pole of the unpowered circuit tester is grounded, while the other end probes for voltage, or vice versa. When a complete circuit is detected, the bulb illuminates. An incomplete circuit will not illuminate the bulb; making you aware that this circuit requires attention.
  • A powered circuit tester, as the name implies, is internally powered and/or grounded depending upon the task selected. The powered circuit tester is typically battery powered, with various visual and audio indicators. It detects complete and incomplete circuits, as well. The difference between the powered and unpowered circuit tester is that the powered circuit tester need only contact one point in the circuit to determine its validity.

cautionExercise caution when using these tools and follow the tool manufacturer’s directions closely. Failure to do so could result in electrical component and/or tool damage.

S.M. Darby

S.M. Darby

I am a freelance author with over 25 years of experience as a professional, ASE certified automotive technician and shop owner, muscle car enthusiast, avid street racer, and classic car restoration specialist.