To check ignition coil resistance and voltage, get your multimeter. Take off all the wiring first. Always pick the right settings on your meter. This keeps you safe. You want numbers that are correct. Know what numbers you should see. This helps you find a bad ignition coil quickly.
Key Takeaways
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Always put on gloves and safety glasses when you test ignition coils. This keeps you safe from shocks and getting hurt.
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Set your multimeter to the right Ohmic range before you start testing. This helps you get the right results and not wrong ones.
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Check your test results with your car’s manual numbers. This helps you know if the ignition coil works right.
Tools and Safety for Ignition Coil Testing
Multimeter and Other Tools
You need the right tools before you test your ignition coil. Grab a multimeter. This tool helps you measure resistance and voltage. You also want gloves and safety glasses. These protect your hands and eyes. If you have a digital multimeter, you get more accurate readings. Keep a clean rag nearby. Wipe off dirt from the ignition coil before you start. Some people use a small screwdriver to disconnect wires. You might need a flashlight if you work in a dark spot.
Tip: Always check your multimeter batteries. Dead batteries give wrong readings.
Safety Precautions
Safety matters when you test an ignition coil. First, disconnect all wiring from the ignition coil. Remove high-voltage wires. This step keeps you safe from shocks. Never touch the ignition coil terminals with bare hands. Set your multimeter to the correct Ohmic range before you test. If you pick the wrong setting, you get false numbers. Double-check your multimeter leads. Make sure they are not damaged. Work in a dry area. Wet hands or tools can cause accidents.
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Always wear gloves and safety glasses.
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Disconnect all wires before using the multimeter.
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Pick the right Ohmic range for your test.
If you follow these steps, you lower your risk and get better results.
How to Check Ignition Coil with Multimeter
Locate and Disconnect Ignition Coil
First, you need to find your ignition coil. Look under the hood. The ignition coil usually sits near the engine. It may look like a small box or cylinder with wires coming out. If you are not sure, check your car’s manual. Once you spot it, turn off the ignition. Wait for the engine to cool down. Now, disconnect all the wires from the ignition coil. Pull off the high-voltage wire and any connectors. This step keeps you safe and helps you get the right numbers when you check ignition coil.
Tip: Take a picture of the wiring before you remove anything. This helps you remember where each wire goes.
Test Ignition Coil Resistance
Now you can test ignition coil resistance. Grab your multimeter. Set it to the Ohms (Ω) setting. You want to check two things: primary coil resistance and secondary coil resistance.
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Primary Coil Resistance
Find the two small terminals on the ignition coil. Touch one multimeter probe to each terminal. Write down the number you see. Most ignition coils should show a primary coil resistance between 0.4 and 2 ohms. -
Secondary Coil Resistance
Next, touch one probe to the positive terminal and the other to the high-voltage output terminal (where the spark plug wire connects). The secondary coil resistance should read between 6,000 and 15,000 ohms. If your number is way off, your ignition coil may be bad.
Note: Always use the correct range on your multimeter. If you pick the wrong range, you might get a false reading.
Test Ignition Coil Voltage
You also need to check ignition coil voltage. Switch your multimeter to DC volts. Reconnect the ignition coil’s power wire, but leave the high-voltage wire off. Turn the ignition key to the “on” position, but do not start the engine.
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Place the red probe on the positive terminal.
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Place the black probe on the negative terminal.
You should see about 12 volts. This is the normal voltage output for most ignition coils. If you see a much lower number, your ignition coil may not be getting enough power.
Warning: Never try to test ignition coil voltage with the engine running. This can be dangerous.
Compare Readings to Specs
After you check ignition coil resistance and voltage, compare readings to the numbers in your car’s manual. Every car is a little different. If your numbers match the specs, your ignition coil is probably good. If they do not match, you may have a problem.
| Test | Expected Reading |
|---|---|
| Primary Coil Resistance | 0.4 – 2 ohms |
| Secondary Coil Resistance | 6,000 – 15,000 ohms |
| Voltage Output (Ignition On) | About 12 volts DC |
Interpret Results
If your readings are in the normal range, your ignition coil works fine. If the numbers are too high or too low, you may need to replace the ignition coil. Sometimes, a bad ignition coil will show no reading at all. That means the coil is open and cannot work.
If you are not sure what your numbers mean, ask a mechanic or look up your car’s specs online.
Troubleshoot Common Issues
Sometimes, you may find strange numbers when you check ignition coil. Here are some common problems and what you can do:
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No Reading or Infinite Resistance: The ignition coil is open. You need a new one.
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Very Low Resistance: The coil may be shorted. Replace it.
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Low Voltage Output: Check the battery and wiring. You may have a loose connection.
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Testing 3-Wire Ignition Coils: Some cars use a 3-wire ignition coil. You will see a power wire, a ground, and a signal wire. Use your multimeter to check voltage between power and ground. Then, check resistance between the other terminals. Follow your car’s manual for the right numbers.
If your readings are not right, do not ignore them. A bad ignition coil can cause engine misfires, poor gas mileage, or even leave you stranded. Always test ignition coil with multimeter if you suspect a problem.
Remember: If you do not feel comfortable, ask a professional to check ignition coil for you.
You want to make sure your ignition coil works right. Accurate testing helps you spot problems fast. If you find bad readings, replace the coil or ask a mechanic for help. Always follow safety tips. If you feel unsure, talk to a professional before you fix anything.
Written by Jack Elliott from AIChipLink.
AIChipLink, one of the fastest-growing global independent electronic components distributors in the world, offers millions of products from thousands of manufacturers, and many of our in-stock parts is available to ship same day.
We mainly source and distribute integrated circuit (IC) products of brands such as Broadcom, Microchip, Texas Instruments, Infineon, NXP, Analog Devices, Qualcomm, Intel, etc., which are widely used in communication & network, telecom, industrial control, new energy and automotive electronics.
Empowered by AI, Linked to the Future. Get started on AIChipLink.com and submit your RFQ online today!
Frequently Asked Questions
How often should you check your ignition coil?
You should check your ignition coil if your car misfires, stalls, or has trouble starting. Regular checks help you catch problems early.
Can you test ignition coil without multimeter?
Yes, you can test ignition coil without multimeter. Look for signs like weak spark, engine misfire, or rough idle. These signs may mean a bad coil.
What happens if you ignore a bad ignition coil?
If you ignore a bad coil, your car may run rough or not start. You could also damage other engine parts over time.
How often should you check your ignition coil?
You should check your ignition coil if your car misfires, stalls, or has trouble starting. Regular checks help you catch problems early.
Can you test ignition coil without multimeter?
Yes, you can test ignition coil without multimeter. Look for signs like weak spark, engine misfire, or rough idle. These signs may mean a bad coil.
What happens if you ignore a bad ignition coil?
If you ignore a bad coil, your car may run rough or not start. You could also damage other engine parts over time.
