Ignition coils play a very important role in the overall function of an engine.
A faulty ignition coil can cause all sorts of problems with your engine, including decreased performance, rough running, and even failure.
Testing your ignition coil with a multimeter is a quick and easy way to determine if it needs replaced. In this article we’ll show you How to test ignition coil with multimeter? and How to Test 12 Volt Ignition Coils?
Make certain the automobile has had time to cool down after driving or idling, then engage the emergency brake. Disconnect the negative battery cable connected to the battery terminal end of the battery.
Look for the engine coil pack in or near the engine. Remove each ignition coil from the engine compartment using a wrench.
The primary winding is made of thick wire and receives direct power from the battery. Connect the positive and negative ends of a multimeter to the terminals on the ignition coil according your instructions.
There are distinct icons on each terminal that represent which lead is positive or negative. For example, a plus and minus sign.
For more reference, consult the owner’s manual. Note the reading on the multimeter and compare this number to the resistance required for the primary winding.
If the reading is outside of the usual range, the resistance coil must be replaced. If the reading is zero, it’s possible that the coil has shorted internally.
However, if the reading is extremely high, it indicates that the coil is open. The coil is operational if there is an open reading.
After receiving the initial charge from the primary winding, it is thinner than the main body and wraps around the coil many times for more energy.
Connect the positive terminal and center pole of the multimeter to the correct leads. If the reading is outside of a suitable range for optimum performance, it’s time to replace your ignition coil.
If your vehicle has multiple ignition coils, you will need to remove and test each one separately. Use a multimeter to take note of the readings, and then reinstall or replace each coil as required.
Because defective spark plugs induce ignition coils to fail, you should inspect the condition of the spark plugs as well. Spark plugs that are faulty can overload and overwork the ignition coils.
If you don’t address the problem with the spark plugs, the coils are likely to fail again.
With the engine off, start by testing the ignition coil on your car with it in park and the key removed.
Locate the ignition coil while opening the hood. It is generally located near or bolted to a bracket relatively close to the distributor, however, its position may vary from vehicle to vehicle.
The spark plugs will be connected directly to the coil in automobiles without a distributor.
Then, disconnect one of the spark plug wires from the plug. These wires usually go from the distributor cap to each of the spark plugs individually. Use gloves and insulated tools when working with your vehicle’s electrical system to avoid injury.
Remove the spark plug after you’ve removed the spark plug wire. A special socket wrench called a spark plug socket is ideal for this.
Next, reconnect the spark plug to its wire. You will be left with a spark plug that is connected to the distributor but not inserted in its “hole.” To avoid electric shock, hold the spark plug with insulated pliers.
Next, take your spark plug (still attached to the wire) and touch the threaded “head” of the plug to any metal part of the engine. This can be virtually any sturdy metal part of the engine block – even the engine itself.
Before you turn on the ignition to check the spark plug, stop the fuel pump. The engine will not start once this is completed, allowing you to check for spark in the coil.
Ask a friend or assistant to turn on the car. By doing this, you’re providing power to the car’s electrical system and, as a result, to the spark plug you’re holding (if your ignition coil is working).
If your ignition coil is functioning as it should, you will see a blue spark jump across the spark plug gap when your friend cranks the engine. This spark will be visible even in daylight. If there is no blue spark, then most likely the ignition coil needs to be replaced.
When you’re done with your test, make sure the car is switched off before repeating the earlier stages in reverse order. Remove the spark plug from its wire and replace it in its hole, then reconnect the wire.
There are other ways to tell if your vehicle’s ignition coil is working properly, in addition to the test mentioned above. If you have access to an ohmmeter – which measures electrical resistance – you can use it to get a more accurate reading of your ignition coil’s effectiveness. However, this requires removing the coil so that you can easily access its terminals.
Your service manual will have the exact instructions on removing your ignition coil. Most of the time, you’ll need to disconnect it from the distributor wire, then unscrew it from its mounting with a wrench. Make sure your car is turned off and has had time to cool before starting this process.
The electrical resistance of each ignition coil is different. If your coil’s real resistance levels fall outside of its specified range, you’ll know it’s broken. Typically, the unique resistance standards for your car may be found in your service manual. If you can’t discover them here, searching on the web for automobile information might help.
Most automotive coils have a resistance reading of 7 – 1.7 ohms for the primary winding and 7,500 – 10,500 ohms for the secondary winding.
The distributor has three electrical connections on each side and one in the center. They may be external (extending out) or internal (depressed in). Connect one lead of your ohmmeter to each of the outer electrical contacts. The primary winding’s resistance is recorded with this test.
Next, complete the circuit by holding one lead of the multimeter on an outer contact of the ignition coil and touching the other lead to the central, inner contact (where main wire from distributor is connected). Measure and record resistance reading – this value is resistance in coil’s secondary winding.
Ignition coils are a crucial aspect of any automobile’s electrical system. If the primary or secondary windings in your car are even a tiny bit outside of the manufacturer’s specifications, you’ll need to replace your ignition coil, as it is most likely broken or malfunctioning
To disconnect your engine’s main negative battery cable, use a wrench.
To disconnect the main ignition coil wire, find the one that leads to the distributor and pull it off of the coil. With a wrench, remove also the small grounding wire attached to its side.
Set your multimeter to the “ohms” function and turn it on.
Probe the center of the coil with one meter, contacting the metal terminal inside. Touch the second probe to the ignition coil’s grounding terminal.
The meter should display 6,000-15,000 ohms; if not, then the secondary winding is faulty.
Remove the meter’s probe from the center terminal and touch it to the terminal bolt on the other side of the coil, near but not connected to, the probe touching the grounding terminal.
The meter should read between 0.4 and 2 ohms. If it doesn’t, there’s a problem with either your primary or secondary winding.
1. Cut the power to your vehicle by disconnecting the battery
2. Use a clip tool to unscrew four screws at the top and bottom of each mounting bracket
3. Unscrew and remove the 4 screws from the brackets
5. Remove the old coil and replace it with a new one.
6. Screws should be tightened in a clockwise manner (opposite directions)
7. After everything has been installed, reconnect the battery.
The average value would be about 0.4 – 2 ohms
A loss of power is one of the initial symptoms that may present themselves when an ignition coil begins to fail.
The Check Engine Light is on.
When your car doesn’t have good fuel economy, it’s costing you money.
The car’s rear end could be heavy, from a transmission rebuild or other work done on the drivetrain. If your vehicle is still backfiring after this has been addressed, there may be issues with exhaust leaks.
The engine is still performing well, but the misfire indicator has come on.
A hard start is defined as an engine that seems to take too long to turn over or stalls before it finally starts.
Wheezing and Coughing Sounds.
Jerking and Vibrating.
A few reasons why there’s no spark could be because the new coil pack is defective, or it could be the crank sensor, ignition module or bad wire in primary circuit.
Another possibility is a faulty ECM/PCM. It would be best to have a technician take a look and give you an estimate for repairs.
So, that’s how you test ignition coil with multimeter! We hope this article was helpful. If you have any questions or comments, please let Amortips.com know in the comment section below and we will get back to you as soon as possible.
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