How to Test Ignition Coil Without Multimeter?

If you own a car, knowing how to test the ignition coil to find out if it is in a good state or not is handy. The benefits of testing your ignition coils are many. For one, it will tell you when you need a replacement, preventing you from being stranded in an unknown location, and tell you when your car needs a trip to a mechanic.

Most car owners only know how to test an ignition coil with a multimeter, while some don’t know how to at all. For that purpose, this guide is here to impact you with the info you need to test an ignition coil without a multimeter. This guide will help you if you find yourself in a situation where you need to test your ignition coil and have no multimeter.

First, we will tell you what an ignition coil is if you do not know it already. Don’t worry; we will break down the meaning to something everyone can understand easily.

An ignition coil starts the engine of a car. It is a crucial component of the working of the ignition system. Traditionally, a car’s battery voltage is 12 volts. Typically, for a car to start, it needs thousands of volts, and that voltage is very low to run your vehicle’s engine. So, the function of the ignition coil is to multiply the voltage, then send it to the spark plugs, which then ignites the fuel-air mixture in the engine’s combustion chambers, causing the car to start.

The Symptoms of a Failing Ignition Coil

A faulty ignition coil results in the engine not running properly. But how can you know when your ignition coil fails? IIn the event of any of the following problems, a faulty ignition coil could be responsible.

The Symptoms Of A Failing Ignition Coil

An Illuminated Check Engine Light

If you drive a modern car, it should have a check engine light. The check engine light will come on when the ignition coil is faulty. Also, if you have an OBD-II scanner, it will display the P0351 ignition code. This code will vary between cars, as all cars are different.

Engine Misfire

When your engine misfires, it is likely that your ignition coil is weak. Your car is misfiring when it gives a sputtering or jerking feel whenever you drive at normal speed. Also, when you stop, misfiring can cause your car to run roughly or shake.

Car Won’t Start/Hard Starts

Remember that a car needs a spark and at the right time to start. Therefore, it won’t be easy to start if your spark plug does not get enough voltage from the ignition coil to ignite that spark.

Rough Idling

Vehicles with a failing ignition coil or an overheating coil will experience rough idling. Rough idling is when your vehicle feels rough as it idles. An overheating coil can cause damage in its primary or secondary windings.

Backfiring

Most backfiring indicates a bad ignition coil. If your car is backfiring, you have to address the issue quickly to prevent your car engine from damaging.

Where to Locate Your Vehicle’s Ignition Coil

Before locating your coil, you should first take precaution measures. These measures are important so that you won’t harm yourself. We suggest you wear mechanic hand gloves and safety glasses.

We usually have one ignition coil for each spark plug for modern cars. This means that if your car has a 6-cylinder engine, it probably has six coils. If your engine has eight cylinders, it’ll have eight coils, and so on. This pattern is not always the case because there are some exceptions. Like some cars have one ignition coil for each two spark plugs. Even so, the ignition coil location varies from one car model to another. Generally, you can locate your ignition coil on top of the engine. First, you must lift the plastic engine cover to access the coils. If you can’t find the ignition coil in your car, jeep, or truck, try identifying the spark plug instead and see its connection. The ignition coil is usually directly connected to the spark plugs.

Where To Locate Your Vehicle'S Ignition Coil

Once you have found your coils, it’s time to start testing them.

Let’s get started

Testing Ignition Coil Without Multimeter – By Swapping Coils

Before now, I assume your engine is off, and your hood is already open. To proceed, the tool you require is a digital code reader.

Testing Ignition Coil Without Multimeter

Procedure

1. Connect Your Code Reader

Connect your code reader to your car. Once connected, it will display error codes like P0354.

This code indicates that you have a problem with the ignition coil. Use the internet if you can’t interpret or understand your engine code.

2. Swap the Coils

Once you have identified the faulty coil from your digital code reader, remove that ignition coil from its present position and swap it with whichever coil of your choice. Let’s say your code displayed a P0354, meaning the ignition coil that connects to cylinder four may be faulty. Disconnect coil four and swap it with coil two or any other.

3. Clear Codes and Run Again

After successfully swapping, clear the engine codes on the digital card reader and rerun the engine. If the ignition coil for cylinder four were terrible, you would receive another error code identifying a misfire in cylinder two. Continue to test all the coils.

In the situation where the error code P0354 is displayed all through, it means that your ignition coil is not bad or not the cause of your problem.

Testing Ignition Coil Without Multimeter – By Using a Power Balance Test

This procedure is another alternative method of testing your ignition coil without a multimeter. This involves using a socket and ratchet set along with a pry tool.

Procedure

1. Switch on Your Engine

Start your car after finding your ignition coil. Run the engine for a few minutes, then recheck the ignition coil.

2. Test the Ignition Coil

Test each ignition coil by removing its electrical connector as the engine still runs. While doing that, monitor the engine’s revolutions per minute (RPMs). If the engine starts making a reduced rough sound, this means the coil is firing and functioning properly. You will notice that while connecting the electrical connector back, the engine’s sound begins to return to normal. Your aim is to find a coil that doesn’t affect the engine’s sound when the electrical connector is being removed or connected back.

3. Determine the Bad Coil

Now, all you need do is test all the ignition coil connect and reconnect the electrical connector, one after the other. Any coil whose engine’s RPMs change is a good coil, while any coil whose RPMs don’t change is faulty. If all the coils are good, it only means that the fault is not from the ignition coil. Maybe the ignition module is faulty.

Frequently Asked Questions About a Faulty Ignition Coil

The following questions are frequently asked about ignition coils.

1. How do spark plugs and ignition coils differ?

People often confuse spark plugs with ignition coils. Also, a spark plug is not part of an ignition coil, and these two parts are separate components and have separate functions. Therefore, the difference is that a spark plug ignites the fuel-air mixture in the engine’s chambers after the ignition coil has sent enough voltage to the spark plug wire, causing the engine to run/start.

2. What is the voltage of an ignition coil?

Ignition coils only take the 12 volts offered by the battery and multiply it into thousands of volts. Say, 30000 – 40000 voltages, on average.

3. Can I drive my car with a bad coil pack?

Your car will keep functioning with a bad coil. So, you can drive it. However, once you feel your ignition coil is bad, test it. When your suspicions are verified, only drive it to the mechanic, where you will get a replacement coil. If you ignore this problem and keep driving your car, the bad ignition will cause a lot of damage to other components of your car, especially the engine.

4. When should I test the ignition coils in my car?

You do not need to test the ignition coils often and only do so when your car is faulty and displaying any of the above symptoms associated with bad coils. If you are not sure of the problem your car is displaying, you can take it to a repair shop and have professionals look into it for you.

Conclusion

The two approaches above are how you can test an ignition coil without using a multimeter to take a resistance test. Learning how to test an ignition coil without a digital multimeter can save you when you can’t find a multimeter around. These approaches are easy to learn, and practicing them will make you perfect. Keep in mind that safety always comes first. So, wear your safety gloves to prevent the engine’s heat from burning your hands or prevent an electric shock from the coil wire.

Once you have tested your ignition coil and confirmed the faulty ignition coil, your next approach should be to head to the repair shop and get the ignition coil replaced. In the case where the coils are not the issue, you should still head to the repair shop for further diagnosing. They might find the fault in your ignition module or spark plugs. A faulty spark plug or plug wire can cause voltage overload, which is bad for the ignition coil if it is not changed immediately.

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