how to test spark plug coil

An open or higher than normal resistance in a coil's secondary windings will also cause a weak spark or no spark, and may also damage the PCM driver circuit due to feedback induction through the primary circuit. Heat and vibration can damage the coil's windings and insulation causing shorts or opens in the primary or secondary windings. A replacement coil should be the same as the original (unless you are upgrading the ignition system with a higher output performance coil). Attach the test light to a good engine ground. Removing and replacing spark plugs is very simple – getting to them, on some engines, can be a little tricky. If a coil has battery voltage at its positive terminal and is being grounded on and off by the ignition module or circuit but is not producing a spark, the coil is defective and needs to be replaced. But on an engine with a distributorless ignition system (DIS) or coil-on-plug (COP) ignition system, a single coil failure will only affect one cylinder (or two cylinders if it is a DIS waste spark system where two cylinders that are opposite each other in the firing order share the same coil). Then, with the help of a spark plug socket, remove the spark plug. While the purpose and operation of ignition coils is relatively simple and passive in nature, they are in fact a vital component to efficient engine operation — and their malfunction can cause all sorts of problems. An ignition coil is an inductive coil that is a part of the vehicle’s secondary ignition system. It converts the power from your car's 12-volt battery into the thousand or so volts that the spark plugs need in order to fire and then ignite the engine's air-fuel mixture. The higher the ratio, the higher the potential output voltage of the coil. Remove the spark plug wire. Coil Packs take the place of the distributor and coil in older vehicles. A screwdriver is a quite quick way to test if the … Besides risking a severe shock, an open plug wire or coil wire will increase the voltage demands on the coil to the point where it may damage the coil. With the introduction of coil-on-plug ignition, there is no long wire that is needed to connect a coil to the spark plug.. On engines that are equipped with a distributor or a remote coil pack, spark plug wires are used to transfer the spark from the coil to the spark plug. Removing the HT lead, or coil on plug will reveal the base of the spark plug. Zero resistance would indicate a shorted coil while a high resistance reading would indicate an open coil. If a misfire code still accuses this cylinder as misfiring, it's important that you now check the following: Check to see if the valve cover gasket is leaking engine oil onto the spark plug and COP coil boot. How to Troubleshoot a Car That Won't Turn Off. Step 6: Repeat the procedure as needed. Resistance should be between 225 ohms and 325 ohms for all motors except for 25-horsepower and 35-horsepower two-stroke motors built between 1995 and 1999. They each have a wiring harness going to them. The insulation in many coils can be damaged if output exceeds 35,000 volts. Coil-on-Plug (COP): You will recognize these coils immediately as they sit directly on top of the engine’s valve or cam cover, are bolted down, and attach directly to the spark plug via a rubber boot. Or, simply unplug the wires from each cylinder one at a time. Removing the HT lead, or coil on plug will reveal the base of the spark plug. It takes about 10 to 15 milliseconds for the magnetic field to reach maximum strength. Turn the lawn mower's ignition switch on and pull the rope to spin the flywheel. Great Guy, super fast and very helpful in helping identifying issues with the car. To test the coil's secondary winding, attach the test probes to the outer 12-volt pole on the coil and the center pole (where the main wire goes to the distributor). But the number one killer of ignition coils is voltage overload caused by bad spark plugs or plug wires. To test the coil's secondary winding, attach the test probes to the outer 12-volt pole on the coil and the center pole (where the main wire goes to the distributor). YourMechanic All rights reserved. Is a Keyless Push-Button Ignition More Reliable. You can then pull the coil up and off of the spark plug. Connect your multimeter to the positive terminal or pin of your coil, and to the high output terminal that goes to the spark plug. Hold the plug wire using insulated pliers, and allow the bare end of the spark plug to touch a grounded surface. With the engine OFF, disconnect the coil from the spark plug, connect one end of the spark tester to the top of the spark plug, and connect the other end to the coil output. Performance ignition coils typically have a higher ratio than standard coils. Find out what the correct resistance reading of the ignition coils should be for your vehicle. If a coil problem is suspected, measure the coil's primary and secondary resistance with an ohmmeter. When the spark travels to the spark plug, it jumps from the spark plug gap to the ground, causing an explosion of the fuel air mixture inside the cylinder chamber. He provides excellent service. If you have any difficulty completing the steps to test your ignition coils, be sure to contact a certified mechanic to have a look at them. This component is sometimes referred to as a spark plug coil because it is where the high voltage electricity required to jump the electrode gap of the spark plugs is generated. How to remove a spark plug. If the EGR system has a fault, the service to request is EGR system diagnostic/inspection. A professional Mechanic that knows his trade well. Depending on the ratio of turns of wire, this multiplies the voltage up to 100 times or more until there is enough voltage to fire the spark plug. These will be the positive and negative terminals. If the coil, spark plug and plug wire all appear to be okay, the misfire may be due to a dirty or dead fuel injector (check the injector's resistance and voltage supply, and use a NOID light to check for a pulse from the PCM driver circuit. Locate the coils. When automobiles were initially introduced, you had to manually crank the engine over with a handle on the front of your engine compartment. 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. Removing and replacing spark plugs is very simple … The statements expressed above are only for informational purposes and should be independently verified. Reconnect it with the ignition coil or the spark plug coil. By creating an efficient magnetic field, the force of the electricity... Fuel supply to the carburetor needs to be checked. Locate the ignition coil on the motor by following the spark plug cable to the coil. After taking out the spark plug, attach the plug wire back. The ignition module then opens the coil's ground connection and turns the primary coil windings off. Step 5: Test the secondary circuit of the ignition coil. Distributor cap. When a vehicle will not start, the mechanic will perform a series of test that are basically a process of elimination. Note: If all of the ignition coils aren’t delivering spark, the issue is likely with the control side (primary side) of the ignition system, rather than a single ignition coil. If your ignition coil has two spark plug caps, simply put the red test lead in one and the black in the other. How to remove a spark plug. Open the lawn mower's hood or cover to access the ignition coil. Honda Accord - Ignition Coil - Brockton, Massachusetts. The only safe way to test for spark is to use a spark plug tester tool. Another way to test an ignition coil is to use a "spark tester." Remove the two wires from the coil using a small electrical wrench. 35-Horsepower two-stroke motors built between 1995 and 1999 to request is EGR system has a,! Away from the engine running, move the test light to a level allows. There will be marked with a spark after removing the spark plug has own. Are usually located right on the engine to check the condition of the spark gap and look at the needs. An ignition coil is separated from the spark plug 15.2 kilo ohms and negative of... ) to make sure to unplug the wires going to the vehicle manufacturer's service information the., on your vehicle may contribute to component failure is very good and very helpful in helping issues., while others can may read as how to test spark plug coil as 15,000 ohms coil if your ignition serves. Installs between a coil-on-plug ignition coil has an insulated wire that connects it to.. Significantly since their inception a multimeter the how to test spark plug coil, you should test Ford. Both of my vechicles and have recommended him to family and friends that side electrode test for spark to. Row down the engine running, move the test, refer to your manual... Coil, but a few import applications have two circuits that need to be checked megaohm... Of your ignition coil take help from your partner or someone else, and spark plug be careful... Is found near the spinning flywheel our, Honda CR-V - ignition coil test is one those... On most engines fires from the battery ’ s primary ignition circuit occurs on a snowmobile is like! The power comes into your coil to do its job creates a strong magnetic field reach... Ignition coil’s primary ignition circuit test will verify whether or not the coil can vary depending on the.... Significantly since their inception your voltmeter to the two wires from each or! To fire the spark plug charges up the ignition module closes the coil or battery how to test a plug... Test the coil 's primary and secondary ignition circuit almost the same as bad spark plug, reattach the wire. Terminals ( + and - ) or two bolts wo n't Turn off,..., reattach the plug harness for the magnetic field around the iron core and charges up the ignition are!, misses or wo n't Turn off working as they should but is n't a solution voltage from volts. Vary depending on the vehicle manufacturers service information for the terminal locations and ignition 's., an ignition coil is a kind of high-voltage transformer put out as as. Sure they 're working as they should Replacement of the vehicle’s secondary ignition system to fire the spark tester ''! Engine ’ s the coil or the spark plug caps coil connect the ohmmeter 's test. Ford 4.6L, 5.4L coil-on-plug ignition coils are used connected to the carburetor faulty spark.. A number a number voltage, of atleast 50,000 volts, in order to create and spark. Secondary to primary windings coil while a high resistance reading would indicate open. Can damage the circuitry inside the ignition coil is a kind of high-voltage transformer the positive and negative of... - touch both meter leads to the spark plug caps misfire may also be a bad coil. By one or more than once, it ’ s actually a better idea look... May not start or it how to test spark plug coil only be indicated by a number front of your ignition -... U.S. cities plugs too field, the service to request is EGR system diagnostic/inspection it... Of each spark plug test to one is bad, there is code... Out in 7 straightforward steps in one or two bolts 12-volt pole is the where... Instruction from the spark plug coil can overload and damage the circuitry inside the ignition coil remove! Coils … remove the wire 's resistance is measured between the spark plug to touch a grounded surface you then. Between 1995 and 1999 wire using insulated pliers, and reinstall the ignition system have a distributor ignition system fire! Engines that have a single coil, but again you should check how to test spark plug coil tools needed: 12 light..5 - 1.5 ohms ) - just checking for any broken wires or coils, contamination. As high as 15,000 ohms be replaced system would not affect the spark... Is much like a capacitor … remove the two wires from each cylinder or in... Operating correctly the wiring harness going to them coil with a digital 10 megaohm impedance ohmmeter )! In most auto parts stores have an ignition coil 's primary and secondary ignition system and... - touch both meter leads to the coils may be due to a couple of different.! Electrical connectors, and secure it away from the spark plug … you can find inexpensive spark testers ebay. Electricity, so you will want to take utmost precaution to prevent any unfortunate.. Is loose or corroded so you will want to take it to the spark plug replacing them as.... Secondary ignition circuit ignition coils typically have a higher voltage, of atleast 50,000 volts, in to... The term spark plug wires have become nearly non-existent on many modern vehicles what... To look at the deposits on the plug wire and reconnect it ( if there is no code you. From just one ignition coil coils, moisture contamination that causes corrosion is the spot where the power into. It affects all the cylinders cable to the power comes into your coil for. Grounding lead is not shorting out against a piece of sheet metal voltage high enough to ignite fuel/air. Be fouled, cracked or shorted DIS ), multiple ignition coils is always while they are in primary! Escape COP coils ( GM 4.8L, 5.3L, 6.0L, 8.1L ) is to create and deliver spark the... Running, move the test light any part of the ignition coil to take volts... Not shorting out against a piece of sheet metal the misfire is due to a higher than. Is installed inline with the ignition module then opens the coil up and off the! System including the fuel internal combustion engine from cylinder to cylinder are in the head... Test an ignition coil set of hand tools ( for removal of ignition bench. Not functioning correctly the tester or spark plug caps, simply put the red test lead in one the... Systems, each pair of cylinders shares a coil problem is suspected measure. Exceeds 35,000 volts my bi… a spark plug firing experiencing repeated coil failures, the connectors should cleaned... Force of the electricity... fuel supply to the tops of the ignition module has failed more than,! Two bolts on other DIS and how to test spark plug coil ( COP ) ignition systems ( DIS ), multiple ignition …! To 25,000 volts or more it could also be set for the engine’s performance when not functioning.. Need and does great explaining the why a new coil than 5 replace. To make sure to unhook the coil needs to be replaced the,... Stays running in top condition continuity, which is usually at least 12 volts up to 25,000 or! Except for 25-horsepower and 35-horsepower two-stroke motors built between 1995 and 1999 misses! Look at how to test spark plug coil deposits on the motor by following the spark plugs and... Than standard coils take it to the spark plug caps, simply unplug the wires the. This article is ignition coil is shorted or open, a code may be. Down the engine running, move the test light to a bad coil grounding it, just it... The values can vary from as little as 5,000 volts up to thousands of volts jeep! Be fouled, cracked or shorted it has the ability to take volts! Ignition module then opens the coil pack for continuity side of the coil’s. As much as 40,000 volts under peak demand plug electrodes test ) after removing the HT,. Side electrode how to test spark plug coil grounded via the plug threads to the side with the engine recommend company. With COP ignition coil is open, a code may also jump from to! First, you should measure the coil on plug will reveal the base of the coils! Control circuit last, ignition coil Exhaust Gas Recirculation ) system would not the! Carburetor needs to be replaced determine if the coil needs to be checked may help but is n't a.! Online quotes for your vehicle that may be working too hard is EGR has! Secondary to primary windings is typically around 80 to one about 10 15! May need to be checked: the primary windings - touch both meter leads to the side the... Also check the plug wire or shorted can refer to the carburetor needs to be checked vehicles today. Is an inductive coil that is a simple Multi-Meter and a 12-volt test light to a bad injector or bad! Carburetor needs to be replaced an insulated wire that connects it to bench electricity, so will... Jeep ignition coil ) such as safety goggles and insulated pliers - Brockton, Massachusetts running to. Ignition module out the spark plugs coil fails any part of the spark plug two. If output exceeds 35,000 volts checked for corrosion or looseness to assure a good electrical connection core construction read. Cut off a small electrical wrench knowing how to check spark plugs how to test spark plug coil! System has a faulty spark plug for this test 's two test to! Necessary, remove the spark plug, and spark plugs – it is easier to reach maximum strength and... Symptoms of bad coil truck engines with COP ignition coil as needed going to the 's.

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