The frustration of a sputtering lawn mower can quickly turn a pleasant chore into a stressful ordeal. The culprit behind this common issue is often a faulty ignition coil, the component responsible for generating the spark that ignites the fuel-air mixture. While diagnosing an ignition coil problem can seem daunting, it’s a task that even a novice DIYer can tackle with the right tools and knowledge. This comprehensive guide will walk you through the steps of testing a lawn mower coil with an ohm meter, empowering you to identify and replace a faulty coil.
What is an Ohm Meter and Why Is It Essential?
An ohm meter is a vital tool for testing the electrical resistance of components in a circuit. The resistance of an ignition coil plays a crucial role in its functionality. When the coil is functioning correctly, it exhibits a specific resistance range. If the reading falls outside this range, it indicates a faulty coil and necessitates replacement.
Getting Started: Gather Your Tools and Supplies
Before embarking on the coil testing process, ensure you have the following tools and supplies:
- Ohm Meter: A digital multimeter is recommended for accurate and reliable readings.
- Lawn Mower Manual: Consult your lawn mower’s manual for specific instructions and resistance values for your model’s ignition coil.
- Safety Glasses: Always protect your eyes when working with electrical components.
- Gloves: Wear insulated gloves for added safety.
- Protective Gear: Consider wearing appropriate clothing to avoid any accidental sparks.
Understanding the Ignition Coil and Its Role
The ignition coil is a crucial part of the ignition system, responsible for converting low voltage from the battery to high voltage required to generate a spark at the spark plug. This process is achieved through a magnetic field that collapses within the coil, inducing a high voltage current.
The ignition coil typically consists of two windings:
- Primary Winding: The primary winding has a relatively low number of turns of wire and is connected to the battery and the ignition module.
- Secondary Winding: The secondary winding has a high number of turns of wire and is connected to the spark plug.
Testing the Ignition Coil: A Step-by-Step Guide
Now that we understand the basics of the ignition coil, let’s move on to the testing process:
1. Disconnect the Ignition Coil:
- Locate the Ignition Coil: Refer to your lawn mower’s manual to identify the ignition coil. It’s often located near the spark plug and may have a distinct, black rubber boot covering it.
- Disconnect the Wires: Carefully disconnect the wires leading to the ignition coil. The wires may be color-coded, and it’s essential to remember their positions for reconnection.
- **Note: ** It’s crucial to disconnect the battery before proceeding with any electrical work.
2. Select Ohmmeter Settings:
- Set the Ohmmeter to the Appropriate Range: Your ohm meter should have several resistance settings. Choose the range that best matches the expected resistance of your ignition coil. Consult your lawn mower’s manual for the specific resistance values.
- Connect the Leads: Connect the ohmmeter’s leads to the appropriate terminals on the ignition coil. Remember, most coils have two terminals.
3. Measure the Resistance:
- Primary Winding: Connect the ohmmeter leads to the primary winding terminals. The resistance reading should be in the range of a few ohms.
- Secondary Winding: Connect the ohmmeter leads to the secondary winding terminals. The resistance reading will be much higher, typically in the thousands of ohms.
4. Interpret the Readings:
- Normal Readings: If the ohm meter readings match the specifications provided in your lawn mower’s manual, the ignition coil is likely functioning correctly.
- Abnormal Readings: If the ohm meter readings are significantly different from the specified values, the ignition coil is most likely faulty.
Interpreting Abnormal Readings
Here’s how to interpret different types of abnormal readings:
1. No Reading:
If the ohm meter displays “OL” (open circuit) or no reading, it indicates that there’s a break in the coil’s winding. This issue signifies a faulty coil requiring replacement.
2. Very Low Resistance:
A very low resistance reading suggests a short circuit within the coil. This indicates a faulty coil and warrants replacement.
3. Very High Resistance:
A very high resistance reading suggests a problem with the coil’s insulation. This problem can lead to a weak spark and needs immediate attention.
Replacing a Faulty Ignition Coil: A Simple Procedure
If your testing reveals a faulty ignition coil, here’s a straightforward procedure for replacing it:
- Purchase a Replacement Coil: Obtain a new ignition coil specifically designed for your lawn mower model.
- Disconnect the Battery: Ensure the battery is disconnected before proceeding.
- Remove the Old Coil: Disconnect the wires and remove the old coil from its mounting location.
- Install the New Coil: Install the new coil in the same position as the old one, ensuring that the wires are connected correctly.
- Reconnect the Battery: Reconnect the battery and test the lawn mower’s ignition system.
Final Thoughts and Tips
Testing a lawn mower coil with an ohm meter is a straightforward process that can save you time and money. By understanding the fundamentals of the ignition coil and the testing procedure, you can confidently diagnose and resolve ignition problems, ensuring your lawn mower runs smoothly and efficiently.
Here are some additional tips:
- Refer to your lawn mower’s manual: Always consult your lawn mower’s manual for specific instructions and resistance values for your model.
- Use a digital multimeter: A digital multimeter provides accurate and reliable readings.
- Safety first: Always prioritize safety by disconnecting the battery and wearing appropriate protective gear.
- Clean connections: Clean the connections to the ignition coil before testing or replacing it to ensure good electrical contact.
By following these guidelines, you can effectively test a lawn mower coil and ensure your lawn mower operates flawlessly. Remember, regular maintenance and troubleshooting can significantly prolong the life of your lawn mower and save you from costly repairs.
FAQ
What is a lawn mower coil, and what does it do?
A lawn mower coil, also known as an ignition coil, is a crucial component of your lawnmower’s ignition system. It converts the low-voltage electrical signal from your ignition system into a high-voltage spark that ignites the fuel-air mixture in the engine’s combustion chamber. Without a functioning coil, your lawnmower will not start.
The coil is typically a small, cylindrical device with two or more terminals. One terminal connects to the ignition system, while the other connects to the spark plug. The coil’s internal windings generate a magnetic field when electricity flows through them, and this field is used to create the high-voltage spark.
Why do I need to test my lawn mower coil?
Testing your lawn mower coil is a crucial step in troubleshooting engine starting problems. If your lawnmower is not starting, a faulty coil is a common culprit.
By testing the coil with an ohm meter, you can determine if it is functioning correctly. This helps to identify whether the issue lies with the coil itself or with other components in the ignition system.
How do I test my lawn mower coil with an ohm meter?
Testing your lawn mower coil with an ohm meter is a relatively simple process. First, you need to disconnect the coil from the spark plug and ignition system. Then, set your ohm meter to the appropriate resistance range for your coil.
Next, touch the probes of the ohm meter to the coil’s terminals, one probe to each terminal. Your ohm meter should read a specific resistance value for your coil type. If the reading is significantly different from the manufacturer’s specifications, your coil is likely faulty.
What are the typical resistance values for a lawn mower coil?
The typical resistance values for a lawn mower coil vary depending on the type of coil. Most coils have a primary resistance ranging from 0.5 to 2 ohms and a secondary resistance ranging from 5,000 to 20,000 ohms.
Always refer to your lawnmower’s manual or the manufacturer’s specifications for the exact resistance values for your specific coil. If the resistance readings fall within the manufacturer’s specifications, the coil is likely functioning correctly.
What if the ohm meter reading is not within the specifications?
If the ohm meter reading is not within the manufacturer’s specifications, it likely means that your coil is faulty. However, before replacing the coil, it’s important to verify the ohm meter’s calibration.
If the ohm meter is reading correctly, and the coil’s resistance is outside the specifications, you’ll need to replace the coil to fix your lawnmower’s starting problem.
What are some other reasons why my lawn mower might not be starting?
A faulty coil is not the only reason why your lawnmower might not start. There are other components in the ignition system that could be causing the problem, such as:
- Faulty spark plug: A spark plug can become worn, fouled, or corroded, preventing a spark from reaching the combustion chamber.
- Broken ignition wire: The wire that connects the coil to the spark plug can be damaged or broken, interrupting the flow of electricity.
- Defective ignition switch: The ignition switch may be malfunctioning, preventing power from reaching the coil.
Can I fix a faulty lawn mower coil?
Unlike some other lawnmower components, a faulty lawn mower coil is typically not repairable. The internal windings of the coil are delicate and susceptible to damage.
If the coil is not generating the required spark, it’s usually best to replace it with a new one. Ensure you purchase a coil compatible with your lawnmower model for optimal performance.