Multi-Meter Series: Meter Overview

We’re also lucky that with that versatility, multimeters have become safer, easier to operate and much more accurate and consistent. Unfortunately, a lot of mechanics and technicians, young and old, aren’t as confident as they could be with a multimeter. And it’s my experience that quite a few use lesser tools like the test light for the wrong sort of jobs.

As the first installment of the multi-meter series, we’ll look at the different, practical, uses of today’s multimeter and how and why one should be used on a nearly daily basis.

When to use a multimeter

For a lot of day-to-day stuff like verifying marker lamps and checking fuses, a test light is more than enough. But the moment that what you’re seeing with your test light (power and ground) doesn’t make sense, then you should go get your multimeter. The reason for this is simple. As I mentioned, a LED test light especially takes very little voltage to light up. A wire meant to deliver 12V to a light can be 99.9% frayed, cut or burned and it will still light up most test lights. A test light is meant to show a presence of power and a ground but tells you absolutely nothing else. Some new, more expensive test leads may give you a direction and voltage, but you are always getting a better reading from a proper multimeter to be sure.

How to make sure a multimeter is reliable

The majority of people who use multimeters are guilty (myself included) of doing very little to make sure a multimer is up to the job. Usually, we’ll make sure there are some zeroes on the screen. Nothing more. We may put the meter to ohms to hear the buzzer, and that’s about it. There are a few more things that take very little time and no talent to make sure we are getting the most out of our multimeters.

One of the most important things we can do has nothing to do with turning on a multimeter but turning it off. First of all, we should turn them off. Pretty much every multimeter today has a screen saver type function that will turn off automatically after a certain amount of time. Leaving it to do so, however, wears on the battery, and a weak battery gives weak results. Consider this to be maintenance.

Check the screen when you turn on your multimeter for either BAT or a battery symbol. Both mean the same thing. It means the battery is weak and needs to be replaced. It’s a good idea to take apart your multimeter once or twice a year and test or simply replace the battery. They are usually about 2-3$ and are worth every cent in reliable readings.

The test leads and overall functioning of the multimeter are the other things anyone can do to make sure the multimeter is working well. Again, when putting the multimeter away, make sure you either disconnect the leads and store separately. If you chose not to, at least make sure there is no tension anywhere on the leads or its tips when stored.

First, turn on the multimeter and put it to volts, at any range or on auto-range. Hold the tips together. The meter should read o.1 or less. If the reading is higher you have a problem. The problem is either with the meter or the leads. To figure this out take a short jumper or even a pin and jump the red and black jacks. If the reading is still high, the meter is at fault and you should find a dealer to repair and adjust the multimeter properly.

If the reading goes to 0.1 or lower, then one or both the leads is at fault. Plug in the red lead, and put the other end in the black jack. If the reading is high, it is a faulty lead and needs to be replaced. If it reads low, the lead is fine. To check the black lead install it in its jack and put the other end in the red jack. The same rule applies. If the reading is high, replace the lead, if not it is fine.

Conclusion

That sums up the basics of using the multimeter in a garage. Of course, there are a ton of uses for a multimeter. For the average and even the advanced mechanic, there are a few basics that we’ll go into later in other parts of the series. We’ll also look at specific tests that we use in garages all the time. For now, we now know when and why to use a multimeter and how to get the most out of yours.

Stay tuned for more.

Drive safe,

Kevin Gauthier