How to Test Chainsaw Ignition Coil with a Multimeter

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The ignition coil is a vital component of a chainsaw’s engine, responsible for generating the electrical spark that ignites the fuel mixture. Over time, the ignition coil can wear out or become faulty, leading to poor engine performance or even a complete failure to start. Testing the ignition coil with a multimeter is a straightforward process that can help diagnose whether it is the source of the problem. In this article, we will guide you through the step-by-step process of testing your chainsaw’s ignition coil using a multimeter.

Understanding the Role of the Ignition Coil in a Chainsaw

Before we dive into the testing process, let’s understand the role of the ignition coil in a chainsaw. The ignition coil consists of two primary components: the primary coil and the secondary coil. The primary coil receives voltage from the ignition module and generates a magnetic field. This magnetic field induces a high voltage in the secondary coil, which is then sent to the spark plug, creating the spark needed for combustion.

Signs of a Faulty Ignition Coil

Determining whether your chainsaw’s ignition coil is faulty is crucial before proceeding with the testing process. Here are some common signs that indicate a faulty ignition coil:

  • Lack of Spark: If your chainsaw fails to produce a spark when attempting to start, it could be due to a faulty ignition coil.
  • Intermittent Spark: Inconsistent or sporadic sparks during startup or while running the chainsaw can also indicate an issue with the ignition coil.
  • Engine Misfires or Stalls: A faulty ignition coil can cause the engine to misfire, resulting in rough idling, decreased power, or frequent stalling.
  • Difficulty Starting: If your chainsaw requires excessive effort to start or refuses to start altogether, a faulty ignition coil may be to blame.

Tools Required for Testing the Ignition Coil

Before we begin testing, gather the following tools:

  • Multimeter: A digital multimeter is essential for measuring the resistance of the ignition coil.
  • Screwdriver: You’ll need a screwdriver to remove any covers or panels to access the ignition coil.

Safety Precautions

It’s crucial to take safety precautions to avoid any accidents or injuries while testing the ignition coil:

  • Disconnect the Spark Plug Wire: Always disconnect the spark plug wire before working on any electrical components of the chainsaw.
  • Wear Protective Gear: Put on safety goggles, gloves, and other appropriate protective gear to safeguard yourself during the testing process.
  • Work in a Well-Ventilated Area: Ensure proper ventilation to avoid exposure to exhaust fumes or other harmful emissions.

Step-by-Step Guide to Testing Chainsaw Ignition Coil with a Multimeter

Now let’s proceed with the step-by-step process of testing your chainsaw’s ignition coil using a multimeter:

Step 1: Preparing the Chainsaw

Before testing the ignition coil, make sure the chainsaw is turned off and the engine is cool. This will prevent any accidental injuries and ensure accurate readings.

Step 2: Locating the Ignition Coil

Consult your chainsaw’s manual to determine the location of the ignition coil. In most cases, it is situated near the flywheel or behind a protective cover. Use a screwdriver to remove any necessary covers or panels to access the ignition coil.

Step 3: Disconnecting the Spark Plug Wire

To ensure safety, disconnect the spark plug wire from the spark plug. This step prevents the engine from accidentally starting while testing the ignition coil.

Step 4: Setting Up the Multimeter

Set your multimeter to the resistance or ohms (Ω) function. Select an appropriate range for testing the ignition coil, usually around 5,000 to 20,000 ohms. Refer to your multimeter’s user manual for specific instructions on range selection.

Step 5: Testing the Primary Coil

Touch the multimeter probes to the primary coil terminals. These terminals are labeled “positive” and “negative” or “primary” and “ground.” Note the resistance reading on the multimeter display. A healthy ignition coil should typically show a resistance between 0.4 and 2 ohms for the primary coil.

Step 6: Testing the Secondary Coil

Next, move on to testing the secondary coil. Connect one multimeter probe to the spark plug terminal or wire and the other probe to the primary coil ground. Record the resistance reading displayed on the multimeter. For the secondary coil, a healthy ignition coil should generally have a resistance between 2,500 and 5,000 ohms.

Step 7: Interpreting the Multimeter Readings

Compare the resistance readings obtained in the previous steps to the specified ranges for your particular chainsaw model. If the readings fall within these ranges, the ignition coil is likely functioning correctly. However, if the readings are outside the specified ranges or show no resistance at all, it indicates a faulty ignition coil that needs replacement.

Troubleshooting Common Issues

In case you encounter any issues during the testing process, here are some troubleshooting tips:

Issue 1: No Resistance Reading

If the multimeter shows no resistance reading, it suggests a break in the circuit or an open coil. In such cases, the ignition coil is likely faulty and requires replacement.

Issue 2: Inconsistent or Erratic Readings

If the resistance readings fluctuate or are inconsistent, it may indicate an internal problem within the ignition coil. Consider replacing the coil if you encounter this issue.

Issue 3: High Resistance Reading

A higher-than-normal resistance reading typically signifies a short circuit or a problem with the coil’s windings. If this occurs, replace the ignition coil.

Replacing the Ignition Coil

If your ignition coil fails the resistance tests or exhibits any of the aforementioned signs of failure, it’s time to replace it. Consult your chainsaw’s manual or seek guidance from a professional to ensure you choose the correct replacement ignition coil for your specific chainsaw model.

Ignition Coil Primary & Secondary Resistance Testing


Testing the ignition coil of your chainsaw using a multimeter is a valuable diagnostic technique that can help identify and resolve engine performance issues. By following the step-by-step guide outlined in this article, you can accurately assess the condition of your ignition coil and take appropriate action, whether it’s replacing a faulty coil or exploring other potential causes. Remember to prioritize safety and refer to your chainsaw’s manual for specific

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