How to Check the Ignition Coil with a Multimeter

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Ignition coil troubles…

With a faulty ignition coil, you are likely to experience some performance issues with your engine. The ignition coil is the component that generates the engine spark in your vehicle.

Faulty ignition coils will produce symptoms that will alert you of a potential issue. Such symptoms include;

1. Your vehicle will not start

Some cars use one ignition coil to create a spark that runs the whole vehicle. In such cars, a faulty ignition coil is likely to affect the vehicle’s starting condition.

2. Engine misfires

The ignition coil is one of the most vital parts of your car ignition system; engine problems are bound to happen when they are faulty. A faulty ignition coil is responsible for your engine misfire, loss of power, loss of acceleration, and rough idles.

3. Engine Check Light comes on

A faulty ignition coil will cause an engine misfire, which will, in turn, trigger the car’s computer, lighting the engine check lights.

If you detect such performance issues with your vehicle, you should perform a particular test. One of these tests is checking your car’s ignition coil with a multimeter.

A multimeter

A volt-ohm meter or commonly known as a multimeter is a tester that measures electrical, current, voltage, resistance, and other values.

There are two types of multimeters:

1. Analog multimeter
  • This type of multimeter has needles that move over the graduate scale.
  • It is less expensive than a digital multimeter.
  • It is also less accurate and hard to read with for most people.
  • It is fragile as it gets damaged after being dropped
  • This type of multimeter usually is for detecting slow changes in voltage.
2. Digital multimeter
  • This type of multimeter is the most preferred one.
  • Though expensive, it’s easy to use and also gives accurate readings.
  • Unlike the analog multimeter’s needle and graduate scale, this device has an LCD screen.
  • The digital multimeter is the most preferred type of multimeter due to its high digital resistance. Once you are equipped with a multimeter, preferably a digital one, then you can begin testing your ignition coil.

There are three popular types of multimeters Designs:

fluke digital multimeter
  • Mostly used to calibrate voltage usage and resistance in your home’s machinery.
  • Most highly recommended for anyone who is not sure which digital multimeter to use.
  • This digital multimeter is the ideal tool for armatures.
Clamp digital multimeter
  • Measures electrical flow using in-build tools.
  • With the ability to measure: Flow of Electricity, Voltage, Power Consumption, Wattage, and Amps
  • This device is recommended for professionals.
An auto-ranging
  • This type of multimeter is mostly used for easy projects. 
  • It is the most highly recommended type of multimeter at-home electrical.
  • It measures one component at a time.
  • This digital multimeter has way fewer settings and knobs.
  • This leaves you with a hands-free device that does all of the hard work for you.

Tools you require;

  • A set of basic hand tools
  • Digital multimeter

Steps to check the ignition coil of your vehicle

Step 1: involves researching your car’s ignition coil specification

The first thing to know is the required resistance reading for your ignition coils. Displayed in range (“ohms” (symbol: Ω), these readings specifications are usually in your vehicle’s factory service manual.

Step 2: Locating the ignition coil, or ignition coils

The ignition coil (s) is usually found on the engine. The ignition coil can also be bolted to the spark plugs or can be mounted remotely around the top of your engine.

Step 3: involves disconnecting the wiring harness of the ignition coils

Mostly held in by one or two bolts, you need to remove the bolts using your hand tools. Ignition coils are quite simple to remove; all you need is to unbolt them.

Step 4: involves testing the primary ignition circuit of your ignition coil

The two ignition coils’ circuits need checking. The ignition coil has both secondary and primary ignition circuit. First, you need to connect your digital multimeter’s negative and positive leads to the negative and positive terminals of your vehicle ignition coil.

Terminals are positively and negatively marked on some coils. You can locate other terminals at the connector.​Ignition coil’s primary resistance should be ranging between 0.4 and 2 ohms. It’s advisable to check at the manufacturer’s specifications for correct readings. 

After checking the readings, if a zero reading is displayed, it means your ignition coil has a problem within the primary winding.

Step 5: involves testing your secondary circuit of the ignition coil.

This step involves connecting the positive terminal of your ignition coil to your digital multimeter, and then to the high output terminal which runs to the spark plug.

The majority of the ignition coils usually have a secondary resistance of about 6,000 to 10,000 ohms. It is better to check with the manufacturer specifications for the required range.

If a zero reading is showing, that means that the coil has a problem and needs replacement. Having excessive reading also means that your coil is open, thus requiring a replacement.

Step 6: Repeat the procedure

This step involves following both Step 4 and 5 for testing the other individual coil if your car has more than one. Ensuring that all the ignition coils are operating in perfect condition is essential.

Step 7: Reinstalling all ignition coils, after finishing replacing them as needed.

Replace any faulty coil after testing all the ignition coils. Next, you need to reinstall the rest of them on to your vehicle. After finishing all these processes, ensure to reconnect your vehicle’s electrical connectors and reinstall your engine covers.

Ignition Coil Replacement cost:

For those who are not good with car repairs, and cannot replace their ignition coil by themselves, you can take your car to an auto repair shop.The cost of ignition coil replacement will depend on the type of vehicle you drive. It will also depend on the auto repair shop you take your car to. Depending on your vehicle, the overall estimated charges should range from $ 150-$600.

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