Rev Up Your Ride: Essential Tips On How To Check Resistance In Ignition Coil

Summary

The ignition coil is a vital component in your car’s engine, responsible for generating the high voltage needed to ignite the fuel-air mixture in the combustion chamber.
Knowing how to check resistance in an ignition coil is an essential skill for any DIY mechanic, as it can help identify a potential problem before it becomes a major issue.
a positive terminal (usually marked with a ” + ” sign), a negative terminal (usually marked with a ” – ” sign), and a secondary terminal (usually marked with a “S” or a “Sec”).

The ignition coil is a vital component in your car’s engine, responsible for generating the high voltage needed to ignite the fuel-air mixture in the combustion chamber. A faulty ignition coil can lead to various engine problems, including misfires, rough idling, and difficulty starting. Knowing how to check resistance in an ignition coil is an essential skill for any DIY mechanic, as it can help identify a potential problem before it becomes a major issue.

Understanding Ignition Coil Resistance

An ignition coil is essentially a transformer that steps up the low voltage from your car’s battery to a high voltage (around 20,000 volts) needed for spark plug ignition. The primary winding of the coil, made of thick wire with many turns, stores energy from the battery. This energy is then transferred to the secondary winding, made of thin wire with fewer turns, to create the high voltage needed to generate a spark.

The resistance of the ignition coil is a measure of its ability to resist the flow of electricity. The resistance of a healthy ignition coil falls within a specific range, which varies depending on the make and model of your vehicle. If the resistance is too high or too low, it can indicate a problem with the coil.

Why Check Resistance in an Ignition Coil?

Checking the resistance of an ignition coil is a crucial step in diagnosing engine problems related to ignition. Here are some reasons why checking resistance is important:

Misfires: A faulty ignition coil can cause misfires, leading to rough idling, decreased fuel efficiency, and engine power loss.
Difficulty Starting: If the ignition coil is not generating enough voltage, it can make it difficult to start the engine.
Engine Stalling: A faulty ignition coil can cause the engine to stall, particularly at low speeds or idle.
Premature Wear: Checking the resistance can help identify potential issues before they lead to complete coil failure, preventing costly repairs.

Tools You’ll Need

Before you begin checking the resistance of your ignition coil, gather the following tools:

Multimeter: A digital multimeter is essential for measuring resistance.
Wire Connectors: These are used to connect the multimeter probes to the ignition coil terminals.
Vehicle Service Manual: This will provide you with the specific resistance specifications for your vehicle’s ignition coil.

How to Check Resistance in an Ignition Coil

The process of checking resistance in an ignition coil is straightforward:

1. Locate the Ignition Coil: The ignition coil is typically located near the spark plugs, usually on the top of the engine. Consult your vehicle’s service manual for the exact location.
2. Disconnect the Ignition Coil: Disconnect the electrical connector from the ignition coil.
3. Identify the Terminals: Most ignition coils have three terminals: a positive terminal (usually marked with a ” + ” sign), a negative terminal (usually marked with a ” – ” sign), and a secondary terminal (usually marked with a “S” or a “Sec”).
4. Set the Multimeter to Resistance Mode: Select the “Ohms” (Ω) setting on your multimeter.
5. Measure Resistance Between Terminals: Connect the multimeter probes to the following terminal pairs:

Primary Winding: Connect the probes to the positive and negative terminals.
Secondary Winding: Connect the probes to the secondary terminal and either the positive or negative terminal.

6. Compare Readings to Specifications: Compare the resistance readings to the specifications provided in your vehicle’s service manual.

Interpreting the Readings

Here’s how to interpret the resistance readings you obtain:

Primary Winding Resistance: If the resistance is within the specified range, the primary winding is likely functioning correctly. If the resistance is too high or too low, the primary winding may be damaged.
Secondary Winding Resistance: If the resistance is within the specified range, the secondary winding is likely functioning correctly. If the resistance is too high or too low, the secondary winding may be damaged.

Troubleshooting Common Issues

If you find that the resistance of your ignition coil is outside the specified range, here are some common issues and potential solutions:

Damaged Winding: A damaged winding can result in high or low resistance readings. Unfortunately, a damaged winding usually means the ignition coil needs to be replaced.
Loose Connections: Loose connections can cause intermittent resistance readings. Check all the connections to the ignition coil and ensure they are secure.
Corrosion: Corrosion on the terminals can affect the resistance readings. Clean the terminals with a wire brush and apply a corrosion inhibitor.

Replacing the Ignition Coil

If you determine that the ignition coil is faulty, you will need to replace it. This is a relatively simple repair that can be done by most DIY mechanics. Here are the general steps involved in replacing an ignition coil:

1. Disconnect the Battery: Disconnect the negative terminal of the battery to prevent electrical shock.
2. Remove the Old Ignition Coil: Disconnect the electrical connector from the ignition coil and remove the mounting bolts holding the coil in place.
3. Install the New Ignition Coil: Install the new ignition coil in the same location as the old one, ensuring the mounting bolts are tightened securely.
4. Connect the Electrical Connector: Connect the electrical connector to the new ignition coil.
5. Reconnect the Battery: Reconnect the negative terminal of the battery.

Beyond Resistance: Other Tests

While checking resistance is a crucial step in diagnosing ignition coil problems, it’s not the only test you can perform. Here are some other tests you can consider:

Spark Test: A spark test involves connecting a spark plug wire to a grounded terminal and observing if a spark is generated when the engine is cranked. This test can help determine if the ignition coil is producing enough voltage to ignite the fuel-air mixture.
Continuity Test: A continuity test can help determine if there is a break in the primary or secondary winding of the ignition coil. This test is performed using a multimeter set to the continuity setting.

Final Thoughts: Maintaining Your Ignition Coil

Maintaining your ignition coil can help extend its lifespan and prevent premature failure. Here are some tips for maintaining your ignition coil:

Regular Inspections: Visually inspect the ignition coil for any signs of damage, such as cracks, burns, or corrosion.
Cleaning: Clean the terminals of the ignition coil regularly with a wire brush to remove any dirt or debris.
Replace as Needed: If you notice any signs of damage or if the resistance readings are outside the specified range, replace the ignition coil as soon as possible.

Rev Up Your Ride: Essential Tips on How to Check Resistance in Ignition Coil