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How Small Engine Ignition Coil Can Be Tested with A Multimeter?

Published by: Tony
Date of Publish:

Does it happen that when you twist the key into the ignition, the car won't start up? Do you know why? This happens because the engines and batteries often have damaged ignition coils. In simple words, the engine ignition coil is one of the engine's elements responsible for producing the needed voltage, which fires the spark plug. If the ignition coil is not in order or is faulty, the engine will not start. In such extreme cases, you will have to replace the ignition coil with a new one.

Sometimes, it could create frustration when you don’t know why your car is not starting. For this reason, you can use a multimeter to ensure your car is not working because of a faulty engine ignition coil. This will ensure if the coil is damaged or not.

What Is Small Engine Ignition Coil and How Is It Different from Other Engines?

A small engine usually has a low-power and small displacement intramural combustion engine used in equipment like concrete mixers, lawnmowers, and generators. Unlike other machinery, a small engine necessitates independent and self-supporting power inputs. These could also include motor scooters, go-karts, and motorcycles.

These engines differ from other engines because of their simplistic design, which features a pull-cord starter, air-cooled cylinder, and capacitor discharge ignition coils. These small engines generally use diesel or petrol as their primary fuel.  

Detailed info, please refer to When do you need to replace the ignition coil, When the ignition coil goes bad

Fundamental Ignition Coil Testing Techniques Utilizing a Multimeter in Small Engine

To make sure that the engine ignition coil is, in fact, the problem that is causing the small engine to behave out of order, you should perform a simple test on the ignition coil. Following are some methods; these methods and techniques that will help you perform the testing process.

Check For the Circuit Continuousness  

If you look closely at the ignition coil, you will observe that a single wire is curled up around a core numerous times. This coiled wire should be uninterrupted and unbroken, and if you notice any damage to the wire, the coil is now useless. To check that the wire is continuous, pass the current through the length without unsheathing it.

Now you check the resistance via an ohmmeter. If the wire is damaged-free, you will get a reading between 2500-5000 ohms. On the other hand, if there is a hindrance in the wire due to any damage, you will receive infinite resistance.

Spot The Location of The Ignition Coil 

To carry out a successful circuit continuity test, you first need to locate the position of the coil as well as the coil's housing; because the engine conceals the coil casing, you might need to disassemble some small parts or pull apart some screws to reveal the housing of the ignition coil.

Another simple way to locate the coil is to follow where the spark plug wire is going as it stops inside a metallic box where the coil is found.

Arranging The Ohmmeter

Before using the ohmmeter, you must appropriately arrange and set up this instrument. To get the correct results out of this device, set it at the 20,000-ohm range. On the other hand, calibrate its dial at the 20K range if you are utilizing a multimeter. Then you will have two leads, one black and one red, and two jacks. Connect the red lead to the simple jack and hook the jack with the ohm symbol to the black lead.

Before using the ohmmeter in the testing procedure, ensure it is in working condition. The right way to check the authenticity of the ohmmeter is to tap the two leads together. Suppose the reading will show a value close to zero. The ohm meter will read one or infinite when both wires are apart and not touching.

Testing Process          

After revealing the ignition coil of the small engine, detach the wires attached to it, but save the ones attached to the spark plug. Later you can disjoin the other end of the spark plug’s wire and move them away from it.

Next, take the red lead and insert its end inside the spark plug’s boot and knock the metal plate along the deepest part of the boot. Scrape the lead on the metal plate to get it in touch with the metal plate.

After this, get the black lead to contact with the metallic coil's housing and observe the digital meter for the readings. Now, if the screen reads a number between 2.5 to 5k ohm, the coil seems to be in decent working condition. If the readings indicated an infinity symbol or one, you have to replace the coil because it's damaged and useless.

How To Test a Small Engine Ignition Coil with A Multimeter?

Usually, testing the small engine ignition coil with a millimeter is an effortless and straightforward task. You just need to follow some basic steps below to successfully conduct the test. You can find more at How to check ignition coil with a multimeter

  • Step 1: Arrange the multimeter appropriately and calibrate its dial to a measurement of 20K ohm
  • Step 2: Look through the user’s manual carefully and gain information on the table containing values of resistance or tolerance. This will help you immensely in the process.
  • Step 3: Place one end of the lead of the multimeter on a spark plug cap high in tension. The other end of the multimeter should be positioned at the base of the coil.
  • Step 4: After performing the above-given process, you should get a value of resistance according to the readings in the value table.
  • Step 5: Station one extremity of the multimeter onto the coil’s kill wire end and the second extremity on the coil's base.
  • Step 6: Once again, you will get the resistance values as stated in the value table. The multimeter should give the resistance values within the designated values provided in the manual under the right circumstances.
  • Step 7: When connecting the terminals of the multimeters to the precise positions of the ignition coil, make sure to keep the specific values given in the table in mind.
  • Step 8: Put one extremity of the multimeter inside the kill wire terminal and lodge the other end inside the spark plug's cap. Note the value of resistance.
  • Step 9: If all your readings given by the multimeter match the values written in the table, you can be calm because your coil is fit and unbroken. And if the readings do not match the table values, your coil is damaged and needs replacement.

Some Important Tips

Before using the multimeter to carry on the test procedure, thoroughly check the ignition coil for any kind of destruction. This step is immensely important because if the ignition coil is even a little faulty, it will not produce the required voltage for the plugs. The multimeter’s screen will either show that the coil is damaged fully or there is a short circuit in your circuit. For this reason, you have to sensibly analyze and compare the readings you get from the ones given in the user’s manual table.

The resistance range has to be between 0.3 and 1 ohm. If you get a low resistance range from the range specified above, it is a sign that the primary coil winding has been shorted. On the other hand, if the readings you get are more than the range given above, it's your cue to replace the ignition coil with a new one.

If you get a reading of infinite resistance, this shows that the primary winding is not finished, and you've got an open circuit. This type of situation will also require a replacement of the ignition coil with a new coil.


It is not necessary that the real cause of your small engine not starting is a faulty coil, so you need to first figure out the reason so you don't just stand around beating yourself up in frustration. Yes, most of the time, it is because of the damaged ignition coil, and if such is the case, you will have to replace a new ignition coil. For this purpose, you also need to carefully learn how to reach the housing of the ignition coil and then how to install a new coil.

While unscrewing and dismantling the screws and metal plates, you must be very careful and vigilant. Remember well to which piece goes where so that you don't make any mistakes. Secondly, you must install the spark plug, place the casing, and tighten it correctly. After installing and screwing around everything the way it was, test the new engine ignition coil to see if it's working; if everything goes right, voila! You have done it and saved yourself some bucks. If it still doesn't work, seek professional help.  

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