The Magical Multimeter: A Must-Have Tool for Diagnosing Anything Electrical

Some people accuse us magazine folks of always trying to get into your wallet. And, frankly, sometimes we do get excited about some new items – whether we’re talking about a new snowmobile or the latest gadget evaluated in our Cold Tested department. But we don’t know if we’ve ever said, “Buy this now!”

We’re going to break that streak right now.

If you’d like to fix or even diagnose anything involving electricity – whether it’s the energy that surges through a car, snowmobile, boat or even a wall socket or a random AAA remote control battery – go buy a multimeter. You won’t regret it.

Available for as little as the price of a couple IPAs or nut-brown ales at a local microbrewery, proper use of a multimeter can save its user tons of time and piles of money by helping to quickly diagnose why something doesn’t work, or why new parts keep failing. And a multimeter is typically easy to use. 

Understanding Snowmobile Electricity

In the so-called “good old days,” snowmobiles had rather simple electrical systems because they didn’t have many electrical demands. If the system could spark the plugs, illuminate a couple of low-power lights and provide some leftover juice for hand and thumb warmers, it was doing its job.

Modern snowmobiles have a lot more going on, and thus higher demands. Just think of all of the places, for instance, from which a sled’s ECU (engine control unit) is pulling data and then making decisions to keep that sled running at optimum level. From high-pressure fuel injection systems and electronic oil pumps to powered exhaust valves, GPS-enabled gauges to electric power steering, on-board air compressors to now even ride systems like Smart-Shox and Dynamix and well beyond, the demand has grown and so have the electrical systems on our machines.

Yet despite all of those extras, the key to on-board electricity remains the same.

Electricity is generated by a sled engine spinning a magnetic dish (the magneto) around a stator that features coils of copper wire. A typical electrical system on a modern snowmobile may have Alternating Current (AC) voltage – the same sort of electricity you’d get out of the wall plug-in in your living room. That power is usually converted to more usable Direct Current (DC) power by a voltage rectifier/regulator on its way to the ECU. Then the ECU distributes the power where it’s needed.

A typical snowmobile battery (if equipped) gives off slightly more than 12 volts of direct current to initially start the machine. But once the engine is running, other components typically use the rotation of the engine to generate the additional power needed to operate most of the aforementioned electrical features. 

The Glory Of The Multimeter

A multimeter is a handy device that can be used to measure electrical properties of a circuit, including continuity, resistance, amperage and voltage for alternating current and direct current.

A multimeter typically has two probes – a positive and a negative – that can be plugged into a couple of different locations on the main unit, depending on what is being tested. Results are shown on a digital readout. You can spend upwards of $600 for a multifunctional, high-end test unit from brands like Fluke or Snap-On, or get a cheapie from Harbor Freight for less than $10.

The dial on meters like the ones shown in the photos must be turned to the appropriate field for the test, and then the setting can be fine-tuned by turning the dial to the proper range within the category. Some more expensive units may be more accurate and can also be auto ranging – which means you don’t have to select AC or DC voltage or the potential voltage range.

There are all sorts of videos online that can teach you how to use your multimeter for multiple functions more efficiently than we’d be able to do here. Most often, you’ll want to find out if you have power at a certain location, if power is able to go through something (like a wire or component, aka continuity), if power is leaking due to a bad ground, or if the right level of power is being transmitted. 

No Engine Spark

Let’s turn to an example.

Most snowmobilers know that in order to run, an internal combustion engine needs a proper mixture of gas and air plus a properly timed spark to ignite it. When a snowmobile will turn over but won’t start (and doesn’t even sound close), the first step is to see which of the three is missing.

In this article, we’ll focus on spark. Especially considering how buried under body work spark plugs can be on modern sleds, it pays to check the simple things first. Is the key on? Is the kill switch raised? Is the tether cord plugged in?

Once those are confirmed, pull off body panels or otherwise gain access to the spark plugs. Pull the plug wire, remove the spark plug from the cylinder, reconnect the wire and set the plug on top of the cylinder head. Then pull the recoil or turn the key and see if spark is arcing at the bottom of the plug. If the spark is blue, you have strong spark. If it’s more yellow or orange, the spark intensity may be sub-par.

If there is no spark, however, test the actual spark plug. Remove the spark plug from the plug wire and set it on a towel or on a non-metal work bench for a test using your trusty multimeter.

To test a resistor plug like what is found in a snowmobile, set your multimeter to the ohm setting (often a horseshoe-looking Omega sign – Ω). Ohms are the way to measure resistance between the points where you placed the two probes. Put one probe on the spark plug’s central electrode (the center point on the bottom of the plug, not the protruding bar underneath it) and the other on the metal top of the plug.

If that plug is allowing power to run through it properly, you should get a reading of between about 4,000 and 15,000 ohms, depending on the plug specs. The number on many multimeters is portrayed in thousands. So, for instance, on the Ski-Doo MXZ 600 E-TEC we used for this story, the test on our spark plugs read 5.17, which equals 5,170 ohms.

If you get a good number, that means the plug’s central electrode is intact and power can move through it. It doesn’t guarantee that the plug is “good,” however. A fouled plug may give you good numbers. If in doubt, just replace the plugs – they’re cheap.

If you’re confident about the plugs, conduct continuity and voltage tests on components further upstream. With voltage, you’ll want to know what spec voltage at the exact point that you’re checking. Test the spark plug cap and wire, the coils, the kill switch, ignition switch, the tether switch before moving to expensive components such as a CDI box, engine control unit (ECU) or stator.

In each case, you want to find out if you’ve got the power to each point, and then if you have the right amount of power. This can also involve sticking probes into wire harness connectors, which can isolate the problem to an individual components or wire that is supposed to be feeding it.

Intermittent failures can be particularly difficult to diagnose. For example, a stator or coil may work fine when it’s cool, but radiant heat or heat generated from the electrical system may cause it to fail. Once more, a multimeter can be used to test resistance, and the value can be compared to the ohm/resistance value published by the manufacturer.

Diagnosing Other Problems

Dim or non-working lights, weak or non-functioning hand and thumb warmers and a lot more can often be diagnosed using a multimeter.

Some shadetree mechanics start by just replacing parts, but that can be an expensive or foolish approach, as the problem may be as simple as a frayed or broken wire, a bad or corroded ground or a blown fuse.

Similarly, sometimes a certain part will be replaced, but then the replacement part will soon fail as well. Only then will you find out that the real problem was that the part was getting too much juice and your voltage regulator was truly the problem.

It takes a little learning, and sometimes you’ll need to do some online research or call a dealership to learn the specs for a certain component. But ultimately a multimeter can be used to diagnose the problem correctly the first time, saving you time and money in the end.