Whether you know them as DMMs, VOMs, multitesters or multimeters, these essential tools are constantly evolving and cropping up on garage workbenches everywhere. There are so many brands and models on the market; you would need a scorecard just to compare them all. Most are purchased for under $100 but can range to $300 or more when including functions for specialized automotive uses.
In many ways, digital multimeters are becoming the “tape measure of the new millennium” with their rich feature sets, easy-to-use functions and extreme versatility. With the addition of a few accessories, test leads, specialized probes and adapters, your DMM can turn test-and-measurement “wheelies” around the garage.
Beyond conducting a bit of product research, comparing prices and determining where to buy a DMM, there are eight crucial factors that you need to consider that will affect your ultimate purchase — and your eventual satisfaction.
1. For what purpose will you use your DMM?
Determine early in the process what you want to do and then, frame your search along the lines of your specific needs.
Will you measure voltage, current, ohms or a combination of all three?
Do you need frequency, temperature or capacitance?
What range is necessary? Some models are specifically designed for low-voltage automotive electronics troubleshooting, while others are right for engine diagnostics.
2. In what environment will you use the test tool?
Do you work in a shop or take your measurements on the road? Will your meter be exposed to moisture, abuse from under the hood, or the tech working in the next bay? Or will you mainly perform delicate, precise measurements on a workbench? The answer can be obvious.
Are you working in daylight or under a dash in the dark? Backlit LCD displays are a necessity under the dash where lights and visibility are low.
3. What automotive diagnostics do you intend to perform?
In addition to the usual diagnostic troubleshooting procedures, here are a few popular systems that need troubleshooting with a DMM:
Electronic powertrain control modules
Electronic fuel injection
Electronic brake controls (ABS)
Electronic ignitions, modules and coils
Air bag modules and sensors
Automatic air conditioning systems
Electronic cruise controls
Electronic level controls
Battery parasitic drain, charging and starting systems
Remote keyless entry, theft deterrent and alarm systems
Steering wheel and column controls
Illuminated entry circuits
4. How do you handle your tools? What is your work style?
Will your meter stay on the bench or will it accompany you on a service call? Or, will you toss it into a toolbox or fishing tackle box? Some DMM models incorporate handy prop-up stands and others feature rugged holsters, tough enough for the most demanding automotive situations. If your style is tough or rough, a few dollars spent for a meter carrying case or holster to protect your investment is well worth the money.
5. Is this purchase a long- or short-term investment?
Will this meter perform as your primary tool? Or will it be a backup to another more high-end meter? Many technicians demand the confidence of always having a backup DMM so they are always prepared. Others have only occasional needs for their DMM. Either way, a mid-priced, multi-function DMM fits the bill nicely.
6. Do you need a complete kit or do you buy each one a la carte?
Fortunately, many suppliers offer complete ranges of test leads, probes, thermocouples and more. Several companies also have task-related kits that employ everything you’ll need to undertake specific measurements.
7. What are the factors of after-purchase service and warranties?
With many meters and test tools being manufactured in other countries, the basic meter warranty is of primary consideration. Who will repair it? Where will you send it for warranty work? Or, does the manufacturer offer an on-the-spot replacement program that saves time, money and hassle? The answers could save you when timely measurements are needed.
8. What is the hidden cost of buying “too much” meter?
Digital multimeters are like any electronics purchase — from audio equipment to computers. You can spend plenty and get a multi-function, multi-task, very complicated unit with all the “bells and whistles”. Be aware, as the options and features mount, so do the potential problems associated with the units’ complexity. And then there’s the cost of learning to correctly use the extra features, employing the proper measurement protocols that assure precise measurement.
High-end meters often host features seldom used. Conversely, you can select a quality, basic meter that is quite straightforward in its feature set, and easy to use and read. Such a plan saves money and avoids potential problems while decreasing your necessary learning curve.
Walking through a meter’s manual before you walk down the dealer’s aisle can make your next test tool purchase a simple task — rather than a frustrating exercise. Tackle the process as you would a major investment worthy of your time and effort. Buy and operate the right meter for you.