You are here because your Ford might not be starting right or misfiring while driving. That can feel really frustrating. But don’t worry, you are not alone. I had the same problem with my Ford too, and I found the exact solution that worked. You can test your Ford ignition coil using a multimeter at home without spending money on a mechanic. In this article, I will show you how to do it in simple steps, with clear and easy instructions that anyone can follow.
Gather the Tools and Safety Gear You Will Need
Before you do anything, you must get the tools ready. Having the right tools and safety gear makes this job simple and safe. The good thing is, you don’t need any expensive tools to test your ignition coil. You just need a few things that you may already have at home or can buy at any local auto parts store.
The first thing you need is a digital multimeter. This small tool helps you measure electrical values like voltage, resistance, and continuity. If you don’t have one yet, try to get a digital one because it is easier to read than an analog one. Most multimeters come with two long test leads—one red and one black.
Next, you need safety gloves. These will protect your hands from electric shocks or heat. It’s also good to wear safety glasses, just in case. You don’t want anything jumping into your eyes while you’re working under the hood.
You also need to have a basic idea of where your ignition coil is located. In most Ford vehicles, it is usually found near the engine, often connected to the spark plugs by wires. If you don’t know exactly where it is, you can check your vehicle’s manual.
You should also make sure the engine is cool before you start working. Never touch engine parts when they are hot. That can burn your hands. So let the car rest for at least 30 minutes if it was running recently.
Lastly, have a clean cloth ready. You can use this to wipe off any dirt or oil from the ignition coil or wires. A dirty connection can give you the wrong reading on the multimeter.
- Digital multimeter (digital type is better)
- Safety gloves and glasses
- Know where the ignition coil is in your car
- Make sure the engine is cool
- Clean cloth to wipe dirt and oil
Remove the Ignition Coil from Your Ford
Once you have the tools ready, it’s time to remove the ignition coil. This part may sound scary, but it’s actually easy if you take your time and follow the steps slowly. You don’t need to be a mechanic to do this. Just stay calm and be careful with each move.
Open your car’s hood and locate the ignition coil. Most Ford vehicles have either one coil per cylinder or a single coil pack for all the cylinders. If your Ford has coil-on-plug systems, the coil will sit right above each spark plug. If it has a coil pack, it may sit on top of the engine and connect to spark plugs with long wires.
Once you find the ignition coil, start by disconnecting the negative battery terminal. This is super important for your safety. You don’t want to get shocked. Use a wrench to loosen the bolt and remove the black cable from the battery.
Now, look at the ignition coil. It should be connected to wires and possibly held in place by bolts. Carefully unplug the electrical connector from the coil. Press down on the clip and pull gently. Don’t yank or force it out.
If the coil is bolted down, use the correct size socket wrench to unscrew the bolts. Keep the bolts in a safe place because you will need them later when you put the coil back. Once the bolts are out, gently pull the ignition coil upward. Some coils might be tight, so give them a little wiggle if needed.
Try not to damage the rubber boot or any part of the coil. Hold it by the plastic part, not the wire or rubber section. Put the coil on a clean surface where it won’t get dirty.
You are now ready to test the coil. This step is done. Take a deep breath—you’re doing great!
- Open the hood and find the ignition coil
- Disconnect the battery’s negative terminal
- Unplug the ignition coil connector
- Unscrew the coil’s bolts carefully
- Pull the coil out gently without damage
Set the Multimeter to the Correct Settings
Now that you have removed the ignition coil, you are ready to set up the multimeter. This part is very important because using the wrong settings can give you false results. You want to test the resistance of the coil, which will help you know if the coil is still working or if it has gone bad.
Take your multimeter and turn the knob to the Ohms setting. The Ohm symbol looks like a little horseshoe (Ω). You may see several ranges on the dial like 200, 2K, 20K, etc. For testing ignition coils, the 200 or 2000 Ohm setting is usually perfect. It depends on your coil type and multimeter model.
Once the multimeter is set, make sure the leads are connected correctly. Plug the black lead into the port labeled “COM” or “common”. Then plug the red lead into the port labeled with the Ohm symbol or “VΩ”.
Now, hold both test leads together and check the reading. It should read zero or very close to zero. This step makes sure your multimeter is working right. If it shows no reading or gives a very high number, you may need to replace the battery in the multimeter.
Also, make sure the tips of the leads are clean. If they are dirty or rusty, wipe them with a clean cloth. Good contact is needed for the right reading.
Once this is done, you are ready to test the ignition coil for resistance.
- Set multimeter to Ohm (Ω) setting
- Use 200 or 2000 range on multimeter
- Plug black lead in COM and red lead in Ω port
- Touch leads together to test if meter works
- Clean the test leads if needed
Test the Primary Coil Resistance
Now it’s time to check the primary resistance of your Ford’s ignition coil. This is the part of the coil that receives power from the battery and sends it to the secondary coil. If the primary coil is bad, your car might crank but won’t start, or it will misfire.
Take your ignition coil in your hand. On the coil, look for the two small metal terminals where the wiring harness plugs in. These are the primary terminals. Take your multimeter and touch the red lead to one terminal and the black lead to the other terminal.
You should now see a number on the screen. For most Ford coils, a healthy primary resistance reading is between 0.3 and 1.0 Ohms. Check your vehicle’s manual for the exact number, but this is a general range.
If the multimeter reads zero, that could mean the coil is shorted. If it shows a very high number or “OL”, that means the circuit is broken or open. Both signs mean the coil is likely bad.
Don’t forget to hold the test leads steady. Moving them around can make the numbers jump or give wrong results. Take a few readings to be sure.
If your reading is within the normal range, the primary part of your coil is fine. If not, it might be time to replace the coil.
- Touch leads to coil’s small terminals
- Normal range: 0.3 to 1.0 Ohms
- “0” = shorted coil, “OL” = open coil
- Hold leads steady for correct reading
- Take reading more than once to be sure
Test the Secondary Coil Resistance
After checking the primary resistance, the next thing to test is the secondary coil. This part of the ignition coil sends the high voltage to your spark plugs. If the secondary coil is bad, your car may start but run rough, stall, or lose power while driving.
Find the large terminal on the coil where the spark plug wire connects. This is usually a single metal post or boot on the coil. Then find the two smaller terminals again. Now, place one lead of your multimeter on the large terminal and the other lead on one of the small terminals.
Your multimeter should show a higher number this time. A normal reading for secondary resistance is usually between 6,000 to 15,000 Ohms (6K to 15K). Again, check your car’s manual to be sure, but this is a common range.
If the reading is very low, it means the coil may be shorted. If it is too high or shows “OL”, then the coil may be open or broken. Either case means your ignition coil is not working right and should be replaced.
Sometimes the metal contacts may have dirt or rust on them. That can cause wrong readings. So, make sure everything is clean before testing.
It’s also a good idea to test from both small terminals to the big one, one at a time. This gives a more full check of the coil.
- Touch one lead to big terminal, one to small terminal
- Normal reading: 6,000 to 15,000 Ohms
- “0” = shorted coil, “OL” = broken coil
- Test both small terminals to the big one
- Clean contacts for better readings
Compare Your Results and Decide What to Do Next
Now you have all your readings. You should compare them with the normal range listed in your Ford’s repair guide or manual. This will tell you if the coil is good or bad. Knowing what to do next will save you time and money.
If both the primary and secondary resistance readings are in the normal range, your ignition coil is likely good. You can now reinstall it back into your engine. Make sure to clean the connections before putting it back.
If either the primary or secondary resistance is outside the normal range, your coil is most likely bad. You should replace it. A bad coil can cause many problems like hard starts, misfires, poor gas mileage, and engine stalling.
When replacing the coil, always get one that fits your car model. You can buy original or aftermarket coils, but make sure they are made for Ford. It’s best to replace coils in pairs or all together if your car has more than one.
After replacing the coil, reconnect the battery, and try starting the engine. If it runs smoothly and the check engine light is off, you fixed the problem!
Keep your multimeter and tools clean and ready for future use. You may need them again someday.
- Compare readings with Ford’s manual
- Normal readings mean coil is good
- Bad readings mean you should replace the coil
- Use the right coil for your car
- Clean parts and test the engine after fix
Final Thoughts
Testing your Ford ignition coil with a multimeter is not hard. You don’t need to be a car expert to do it. You just need the right tools, some patience, and simple steps to follow. Doing this yourself can save you a lot of money and help you fix your car faster. Always be careful, take your time, and follow each step closely. When you understand how your coil works, you feel more in control of your car problems. Keep learning and stay safe out there.
Frequently Asked Questions (FAQs)
Is it safe to test an ignition coil by myself?
Yes, it is safe to test an ignition coil by yourself if you follow the safety steps carefully. Always disconnect the battery first before touching any parts near the engine. Wear gloves and safety glasses to protect yourself. Let the engine cool down before working. Also, make sure you use a digital multimeter that is working correctly. Take your time and don’t rush. Testing an ignition coil does not need you to deal with high voltage directly, so it is a low-risk job when done right.
Can a bad ignition coil cause the engine to shake?
Yes, a bad ignition coil can cause your engine to shake or run rough. The ignition coil sends power to the spark plugs. If one coil is not working, that cylinder won’t fire properly. This causes a misfire, and the engine may feel like it’s shaking, especially at idle. You might also notice poor fuel mileage and a check engine light. Fixing or replacing the bad coil will often make the engine smooth again and stop the shaking.
Do I need to remove the coil to test it?
In most cases, yes, you should remove the ignition coil to test it properly. This lets you touch the terminals directly with the multimeter and get clear readings. Leaving it in place can make it hard to reach the terminals or may give wrong results. Also, testing while the coil is still connected to other parts might damage your multimeter or confuse the readings. Removing it only takes a few minutes and makes the test more accurate.
Is it normal for a coil to get warm?
Yes, it is normal for an ignition coil to get warm while the engine is running. The coil works hard to change battery voltage into high voltage for the spark plugs. This work makes it warm. But if the coil gets very hot or you smell burning, that’s not normal. A coil that overheats may be going bad and should be tested. If the coil is too hot to touch after just a short drive, it could be a sign that it’s failing.
Can I drive with a bad ignition coil?
You can drive for a short time with a bad ignition coil, but it is not a good idea. A bad coil can cause misfires, engine shaking, and poor fuel use. It can also damage other parts like the spark plugs or catalytic converter. If your car runs rough or shows warning lights, it’s best to test and fix the problem soon. Driving too long with a bad coil can turn a small problem into a big and expensive repair.
Do I need special training to use a multimeter?
No, you do not need special training to use a multimeter, especially for simple tests like this one. A digital multimeter is easy to use once you know how to set it and where to place the leads. Just follow the instructions and take your time. If you are testing resistance, you are not working with live electricity, so it’s safe. You can also watch video guides or read your multimeter’s manual if you are unsure. Many beginners use multimeters without problems.
Is it better to replace one coil or all of them?
If only one coil is bad, you can replace just that one. But if your car is older or the other coils have high mileage, it may be smart to replace them all. This is especially true if your Ford has coil-on-plug systems. Replacing all at once can stop future problems and make the engine run smoother. Some people choose to replace coils in pairs. It depends on your budget and how long you plan to keep the car.
Can a bad coil cause the check engine light to turn on?
Yes, a bad ignition coil can cause the check engine light to come on. When a coil does not send the right voltage to the spark plug, the engine misfires. The car’s computer sees this and stores a trouble code. That code turns on the check engine light. If you scan your car with an OBD2 tool, it may show a code like P0301 or P0351, which points to coil problems. Replacing the bad coil will usually turn the light off after a short drive.
