How to Check a Coil Pack with a Multimeter

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How to Check a Coil Pack with a Multimeter

When suspecting that there is something wrong with your car’s ignition coil, the best way to assess for the primary problem is by using a multimeter. Usually, a faulty coil might result in engine misfire, lowering fuel economy as well as staling. Your vehicle will be prevented from running when operating on a faulty ignition coil.

When having an issue with your car’s ignition coil, you should test the coil using a multimeter in order to determine which one is experiencing the problem. Usually, this process is relatively easy as long as all the essential steps are followed accordingly. Therefore, in this article, we shall be focusing on how to check a coil with a multimeter.

Assessing for fault symptoms in a coil

You will want to commence by checking for symptoms related to faulty ignition coils. Once this is done, you should follow it up by testing the ignition coils using a digital multimeter.

Coils operate by taking energy from the battery, which is usually 12 volts and then converts it into high volts of 50,000 volts and more to create a spark. This amount of energy will travel through a distributor into the sparking plugs and then ignites the fuel. Some cars feature one to two ignition coils that are responsible for multiple spark plugs while other car models use one ignition coil in every spark plug.

Whether your car features one coil or eight coils, you will have to remove all of them when checking for faults. Before you commence on the test, ensure you have all the essential tools required for the examination and an Ohmmeter or a multimeter.

On the initial diagnosis, you should assess for common symptoms of a faulty ignition coil since you will have to remove every coil before testing them. By doing this, you will be able to save plenty of time if you discover a faulty symptom within a coil. Here are some common symptoms of a defective coil you should be looking for;

Backfiring

Whenever your car backfires, it is difficult not to notice. You will hear a sound similar to that of a shotgun blasting and your car might lurch, and black smoke will gush out of the tailpipe. On the dashboard of your car, the check engine sign will turn on, and you might smell gasoline. Usually, this situation often occurs when an unused fuel gets into the exhaust pipe and then burns on its way out.

Low fuel pressure might be the issue; however, at times the ignition coil will have to be blamed. Faulty ignition coils often affect when a spark plug ignites, causing an improper timing.

Stalling

If you have driven a car that stalls, you probably understand how frustrating it can be when dealing with abrupt starts and stops. This situation is extremely dangerous when it occurs in traffic. One or more faulty ignitions coils can lead to stalling by sending unusual sparks into the spark plugs. The uneven electrical charge is the chief reason as to why your engine is not running smoothly.

Lower fuel economy

Whenever an ignition coil transmits little energy to a spark plug, then your car will be consuming extra fuel. This is because extra fuel is the only way it can be set to power. This will cause a tank of gas to cover fewer miles than usual. This will indicate that you have one or more faulty ignition coils.

Difficulty in starting your car’s engine

When you have a problem with the ignition, you might consider checking on the battery as most people do. However, what if your car battery is in good condition? It is recommended to check on the car ignition coils. They often cause problems to cars if they are faulty; especially for cars using one ignition coil per an ignition configuration. Your car might run if you only have a few ignition coils faulty; however, it will be a bit difficult to ignite it.

Once you have these symptoms assessed and it happens that your car is facing any of the above symptoms, it is time you test your ignition coils with a multimeter.

Checking for faulty coils using a multimeter

Safety

Safety is the number one priority when testing for faulty coils with a multimeter. First and foremost let your car cool down before commencing on the test. Furthermore, ensure that you have put the emergency brake on. Once this is done, open up the hood and disconnect negative cables from the battery.

Removing the ignition coils

Locate you’re the ignition coils of your car. They are often located near the engine. It would help if you disconnected all mounting bolts that are holding the ignition coils and then remove every coil one by one.

Testing the primary winding

Every ignition coil features two different coils that are wrapped around each other. These are the primary and secondary winding. Usually, the primary winding coils are made of heavy wires, and they are responsible for receiving energy from the battery. You should first test this part of the coil;

  • Check for the correct resistance reading from the car’s manual.
  • Connect the positive and negative leads of your multimeter to the ignition coil terminals. You should ensure you have connected them accordingly to prevent any accident from occurring. The terminals are often marked to indicate the positive and negative sides.
  • Check the result on your multimeter and compare it to the resistance specification available in the car’s manual.

You will have to replace the coils when the final readings aren’t corresponding to the car’s manual. Zero results indicate that the coil shorted internally, whereas high reading indicates that the coil is open. However, if they are okay, you should consider checking on the secondary winding.

Testing the secondary winding

Usually, the secondary winding is a thin wire which coils several times, and it is responsible for receiving the energy from primary winding and sends it to a spark plug. Testing it is similar to the primary winding;

The leads of your multimeter should be connected to the positive terminal as well as the center pole. Usually, the center pole is where the chief wire is attached to a distributor.

You should then compare the result to the resistance specification that is available in your car’s manual.

When the results are not corresponding, you should consider replacing the ignition coils.

Conclusion

Whenever your car features more than one ignition coil, you should consider removing and each one and tests them individually. Furthermore, when replacing the faulty coils with new ones, they should be of the same kind.

About the Author Dan

Just a random guy who likes to build things. Providing tool knowledge, appliance/device testing tips, and DIY project info in an easy-to read & non-intimidating style.