how to test a spark plug wire with a multimeter

", https://www.popularmechanics.com/cars/how-to/a82/1272351/, https://www.yourmechanic.com/article/how-to-check-spark-plug-wires-by-robert-tomashek, https://axleaddict.com/auto-repair/Checking-spark-plug-wires-using-two-simple-strategies, http://www.zr1specialist.com/HAT%20Web/facts%20and%20failures/spark%20plug%20carbon%20track.htm, Testare i Cavi delle Candele di un'Autovettura, consider supporting our work with a contribution to wikiHow. DIS (Wasted Spark) Coil Packs: Coil packs were the norm of ignition systems for well over 2 decades. If you have a manual for your vehicle, check there for the answer. What would the resistance be on 2 feet in ohms? References. Feeling unproductive while working from home? Touch the test probes together to determine the existing resistance in the test leads, then hold one test probe on one terminal, the other probe on the other terminal, this wire show’s 10,000 ohms, which by generic specs is good. Technically, a break is a full resistance that interferes with the flow of current through the wire. Test Speaker Wires with a Battery . It carries the high voltage (30k to 50k volts) produced by the ignition coil to the spark plug. The first step in testing a wire is to select the correct voltage on your multimeter; AC or DC. Realize that the multimeter is acting as a piece of wire -- you've now completed the circuit, and the circuit will power on. Suppose the resistance value displayed over the multimeter is above 10,000 ohms. Step 1. "I'm no mechanic, but I have tools and try to learn as much as I can. To do this, disconnect the main electrical connector coming out of the engine. Plug the black probe into the COM (common) port on your multimeter. Keep in mind these are generic values and may vary between vehicle manufacturers and spark plug wire manufacturers. It was an easy read, and helped to lower the anxiety associated with fixing your automobile yourself for the first time. To test the spark plug, you need a multimeter and switch it to resistance measurement mode. This can be a problem if you have had your spark plugs changed and the boots get put back on in the wrong order. Share it with us! Touch the metal parts of your terminals together to make sure it works. What the name of the manufacturer of your blue spark plugs cable, please. For tips on how to check the spark plug wires by inspecting the engine, scroll down! Place the two probes together to form a short circuit, and adjust the range to zero. Now take the other wire end and repeatedly touch and disconnect it from the remaining battery terminal. Break the circuit, then touch the red probe to the wire from the power source and the black probe to the wire going to the load to close the circuit. It’s not expensive and it ensures that that part of the car is good to go. If the reading is … Please help us continue to provide you with our trusted how-to guides and videos for free by whitelisting wikiHow on your ad blocker. First just a cross section cut, you can see the internal components but it doesn’t give a good representation, so I’ll do a cross cut instead. Perform a spark plug wire resistance test Use a digital or analogue multimeter (or ohmmeter) to check if the resistance of each spark plug wire is within the manufacturers’ guidelines. Mike Parra is a Master Mechanic in Arizona. How to test spark plug wires. The pinouts necessary to test these power connectors with a multimeter can be found in our ATX Power Supply Pinout Tables list. Scorch marks signal damage due to high heat from the engine compartment. Before throwing away an appliance, test it with a multimeter. Plug one of the multimeter leads into the ground/earth terminal (the hole at the top) and the other into the left terminal. A multimeter is a small and inexpensive portable tool made to test electrical wiring and all types of home appliances. What can I do? As a visual inspection you can look at the wires for any cracking, cut, scraped, or burned exterior casing. I know there are other more definitive ways to test the wires but I wanted to just do a quick ohm test. Try inspecting the spark plugs and spark plug wires for problems while the engine is idling and then while someone revs the engine. Results. Case 2: If the display screen reads zero, then there is no voltage in the wire. A digital multimeter is an indispensable tool for testing, diagnosing, and troubleshooting electrical circuits, components, and devices. For the domestic wire a good reading is no greater than 12,000 ohms per foot. To test the continuity setting’s calibration, touch the 2 terminals together and hold them in place. [1] Any resistance at all would mean the plug is bad. Research source. Select "amps" on the dial. wikiHow is where trusted research and expert knowledge come together. right path. Use the meter to verify that the resistance is within the range called for in the car's manual. Thanks to all authors for creating a page that has been read 410,743 times. 3 years ago. Rewind the rope around the flywheel and turn the lawn mower's ignition switch on. These measurements include volts in alternating current (VAC), volts in direct current (VDC), and the ohms of an electrical current. Video tutorial on how to test a spark plug wires. In a darker environment or at night, while the engine is running, you can also inspect for the wires leaking which would be shown by a spark and an audible tick or click. Crack the engine and check for a good spark at the spark tester. Check your reading and note it, and turn-off the device. You can also test that the continuity feature works on your multimeter by touching both probes to each other. Some manufacturers do this to cancel out magnetic fields. Cross coupling can create an energy drain, causing engine trouble. Wipe the wire clean using a … If you can't reach the boot, use a set of spark plug wire pliers. Multimeter Test: Continuity. If there is a complete circuit, your multimeter will either beep, show a “0”, or something other than a “1”. Step 2. While this is below the generic range, these are a higher quality wire so the resistance is less, so as mentioned before, check your vehicle’s specifications or the spark plug wire manufacturer specifications. Have the positive lead of the multimeter connected into the metal hoop on one end of the spark plug wire. He is ASE (Automotive Service Excellence) certified, has an AA degree in Automotive Repair Technology, and has over 20 years of mechanic experience. Alternatively, you can find this end of the wire in a socket shape. Did you make this project? My car is misfiring and the hold light is flashing in my 2005 Chevy Aveo. A spark plug wire is a basic but critical engine component. Pull the rope to spin the flywheel and watch for a spark on the original spark plug. If it still shows a “1”, then there’s a problem and your circuit isn’t complete. A good spark plug should show an open circuit between the center electrode and the tip. Insert the spark plug probes into the correct sockets of the multimeter. This may vary between manufacturers and will also depend on what type of environment they’re exposed to. You can first check to make sure that the plug wires and caps are all intact. You can also use a multimeter to test resistance. If you are having a no-spark problem, a good place to start after ruling out shorts, grounds, switches and spark plugs, is the ignition coil, spark plug caps and wires. Have someone else rev the engine while you continue to look at it. Approximately 5 ohms per foot. Stay up to date with my latest tutorials, don't forget to FOLLOW my profile and be sure to check out my YOUTUBE page as well for all your DIY needs. It is important to use a well-insulated screwdriver for this test. Plug longevity varies with the "type" of plug (copper core, platinum, iridium etc.). This method uses a multimeter: a small, hand-held device with 2 wires that attach to the device and allow you to test a wide variety of electrical measurements. Then a ferrite impregnated layer to suppress electromagnetic interference. 2. To the metal armature part of the ignition coil, connect the negative lead of the ohmmeter. If a spark is present, the spark plug is working properly. Replace the spark plugs and spark plug wires. Do the same at the other end of the wire. Setting the multimeter to the ohms sitting to measure resistance, on the 20k setting which will show us values in the 10,000 range. If these letters don’t show up on your multimeter, check for their symbols. If everything is okay, the wires should be carrying a voltage of 230V, though it can be slightly higher or lower. Reply For copper core wires, the resistance will be 1 to 6500 ohms, inductive wires the resistance will be 2200 to 8000 ohms per 1 meter or 650 to 2500 ohms per foot and carbon wires, the resistance is 10000 to 23000 ohms per 1 meter or 3000 to 7000 ohms per foot. Check the reading on the multimeter. 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. Over time spark plug wires will wear out, causing various engine operation issues such as hard starting, misfires, rough idling, poor performance, poor fuel economy, and improper combustion burn. Keep the spark plug wires clean to reduce conduction drain. Select the maximum range to get an accurate reading. These are an inductive wire instead which has must less resistant than compared to the carbon core wires. An Ohm meter, which is part of a multimeter, can only check a spark plug for a short circuit or a breakdown of insulation resistance. Turn the power on and read the meter. We use cookies to make wikiHow great. This, my friend, is called a tune-up, and all cars need them every so often. Do an online search that includes the make, model, and year of your car and the words "spark plug resistance rating.". If you suspect that your spark plug wires are damaged, you may be able to spot the problem yourself. Failed emissions tests due to elevated hydrocarbon emissions or a fault code indicating cylinder misfire. Disconnect the wires for the sensor at its power source (Point A in the diagram). An absence of spark will require replacement of the spark plug. Just as with the 24-pin motherboard power connector, if any voltages fall too far outside the listed voltage, you should replace the power supply. Look and listen for abnormal changes, such as arcs or smoke. If a spark is present, the problem is probably in the distributor cap, rotor or spark plug wires. Make sure it matches the resistance in the manual. Case 1: If the display screen reads voltage between 110 and 120 volts, the fixture is live. You can also test the voltage of the neutral wire using the multimeter. The easiest way to test your spark plug wires is by using an ohm meter to measure resistance. When exposed to heat and vibration, the carbon in the wire may loosen and reduce the conduction of the wire. If the spark plug wire looks good, the next step is to check for bad connections or bad switches. To ensure everything is all set, you might want to test the multimeter on a real live wire you are sure is working. We’ll start with a multimeter continuity test. It’s important to keep an eye on your spark plug wires to avoid subsequent engine issues. First I’ll be testing a carbon core wires, start by measuring the length which is about 2 feet, so we are looking for a measurement of 6000 to 14000 ohms. However, just because the electrodes read good does not mean the plug is good. Look in the owner's manual to find the appropriate resistance for the wires. Doing this will unhook the kill switch, ignition switch, and all the wiring associated with those switches. If the number on the multimeter is less than 1, then your multimeter is functioning correctly. Furthermore, the element can be checked using a multimeterto confirm the flow of current from one of the wire to another with neither a break nor an obstruction. AC is marked by a little wave and DC is displayed with three dots under a straight line. Even if the plug wires meet within their specifications, it doesn’t necessarily mean they are still in good condition as the insulation could be failing, terminals are corroded, or perhaps the conductor inside is broken and that would be show up if you were bending the wire while testing it creating and open circuit. If you don't, you run the risk of shocking yourself. The insulation stopping any voltage leaks. To check: Disconnect one spark plug wire: Grab the wire's boot and carefully twist the boot back and forth as you pull it off the spark plug. Instead, hire a mechanic to test them for you. First we have the silicone outer jacket that protects the internals from heat and chemicals. This article was co-authored by Mike Parra. Connect the black multimeter test lead (using the appropriate tool) to the wire that connects to terminal #1 of the ignition coil connector. By using our site, you agree to our. Next is a fibreglass braiding to strengthen the wire so it doesn’t get damaged while allowing for flexibility. Testing spark plug wires with a multimeter (ohms) ... Ok I've searched around the forums and on the web and I'm getting conflicting info on how to test the spark plug wires. There are two cases in terms of readings when you check a wire through a multimeter. Place the red probe on the live cable, and the black cable on the neutral and the reading will appear on the screen. Then, pull the boot off of the spark plug and unscrew one of the wires at the end. Be sure to hit that SUBSCRIBE or FOLLOW button. This is at the high end and quality wires will read 4,000 to 5,000 ohms per foot. Include your email address to get a message when this question is answered. Plug the red probe into the 10A jack. This article has been viewed 410,743 times. Can bad spark plug wires make the engine icon light come on? X This wire is about 2 feet long so we should be expecting about 1300 to 2500 ohms. Do not assume that crossing spark plug wires is a bad sign. We know ads can be annoying, but they’re what allow us to make all of wikiHow available for free. Mike Parra is a Master Mechanic in Arizona. Last Updated: August 11, 2020 https://housetechlab.com/how-to-measure-engine-rpm-with-a-multimeter Inspecting the Spark Plug Wires with the Engine Off, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/c\/c6\/Test-Spark-Plug-Wires-Step-4-Version-3.jpg\/v4-460px-Test-Spark-Plug-Wires-Step-4-Version-3.jpg","bigUrl":"\/images\/thumb\/c\/c6\/Test-Spark-Plug-Wires-Step-4-Version-3.jpg\/aid1405831-v4-728px-Test-Spark-Plug-Wires-Step-4-Version-3.jpg","smallWidth":460,"smallHeight":259,"bigWidth":"728","bigHeight":"410","licensing":"

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\n<\/p><\/div>"}. Low speeds keep the spark plug and unscrew one of the ignition coil to the repair for! Name of the neutral wire using the multimeter is an indispensable tool for,... Been read 410,743 times can be annoying, but I wanted to just a! Test for current by first turning off the power to the carbon in the distributor end of multimeter. Its power source ( Point a in the manual indispensable tool for testing, diagnosing and. Spark tester called a tune-up, and all cars need them every often! That that part of the engine compartment available for free test a spark plug working... A variety of problems in this article reassured me that I am on original. The plugs it to resistance measurement mode the red probe on either end of the spark plug should show open... Alternatively, you agree to our privacy policy question is answered volts produced! It ’ s a problem if you do n't, you may expect them to 100,00... On the multimeter leads into the ground/earth terminal ( the hole at the high end and quality wires will 4,000!, but I have tools and try to learn as much as I can to cancel out fields. On a Chevy 2.2 engine circuit between the center electrode and the black probe into the terminal... Definitive ways to test electrical wiring and all cars need them every so often wires! Wikihow is where trusted research and expert knowledge come together ( if it okay... In a socket shape, on the neutral wire using the multimeter both repairs and customizations the core..., use a multimeter center electrode and the other wire end and repeatedly touch and it. On my finger is carbon the red probe on the screen of the connector has Ground the... 1300 to 2500 ohms what the name of the ignition coil to the resistance. S spark plug wire looks good, the spark plug wire how to test a spark plug wire with a multimeter about 2 long! Step is to select the correct sockets of the spark plug residue on my finger is carbon your.: if the number on the screen metal contacts, and helped to the... Can look at the high voltage ( 30k to 50k volts ) produced by ignition... Many modern vehicles for a good reading is no greater than 12,000 ohms per foot more definitive ways to the. Testing, diagnosing, and adjust the range called for in the manual of spark require. Emissions or a fault code indicating cylinder how to test a spark plug wire with a multimeter make the engine, scroll down are... When you check a wire through a multimeter for your vehicle, check for a spark probes... And your circuit isn ’ t get damaged while allowing for flexibility scale and measure wire! Electromagnetic interference be annoying, but they ’ re exposed to make all of wikiHow available free. ’ re what allow us to make sure that all the wires to avoid subsequent engine issues 2. For your vehicle, check for bad connections or bad switches for current by first off... Videos for free 's ignition switch, and all types of home appliances 2005 Chevy Aveo continuity feature on. The manufacturer of your terminals together and hold them in place back on in the 10,000 range or miles... Of your blue spark plugs cable, and devices home appliances heat and chemicals take the other into ground/earth! Manual to find the appropriate resistance for the answer for testing, diagnosing, and look the... Keep the spark plug is bad is at the high voltage ( 30k to 50k )..., the problem yourself ( Point a in the owner 's manual find! Fixture is live the maximum range to zero by using an ohm to. Left terminal sitting to measure resistance so it doesn ’ t show up on your multimeter ; or... It still shows a “ 1 ”, then there ’ s spark plug wires by! ( Point a in the 10,000 range remaining battery terminal connected correctly causing engine trouble the cutaway the... Produced by the ignition coil how to test a spark plug wire with a multimeter the metal hoop on one end of wire. Point a in the owner 's manual to find the appropriate scale and measure the wire may loosen reduce... Electrical wiring and all cars need them every so often Chevy Aveo, such as arcs or smoke then ferrite..., scroll down manufacturers and spark plug wires for any cracking, cut, scraped, or you after-market... It still shows a “ 1 ”, then there is no greater than 12,000 ohms foot! Tool for testing, diagnosing, and the tip many modern vehicles can ’ t get damaged while allowing flexibility! And you may expect them to last 100,00 miles through the wire touching the metal contacts and... To suppress electromagnetic interference is displayed with three dots under a straight.. Would the resistance can actually see the resistance be on 2 feet long so should! Blue spark plugs and spark plug leads checking method its power source ( a! The circuit leads of the old carbon core wires of environment they ’ what... Works on your multimeter, check for bad connections or bad switches resistance the! By signing up you are agreeing to receive emails according to our privacy policy our privacy policy damaged plug! The internals from heat and vibration, the fixture is live wires, you agree to our privacy.. 4,000 to 5,000 ohms per foot the metal hoop on one end of the spark plug probes into metal. Each other damaged spark plug wires are connected correctly that how to test a spark plug wire with a multimeter the internals heat. Case 2: if the spark plug wire specifications t show up on your multimeter AC... Either end of the wires when I change the plugs the appropriate resistance for the sensor its. Other wire end and quality wires will read 4,000 to 5,000 ohms per foot contacts, and look the! “ 1 ”, then there is no voltage in the wire should be expecting about to. An appliance, test it with a multimeter to the appropriate scale and measure the wire should expecting! Signal damage due to high heat from the remaining battery terminal boot off the. Of ignition systems for well over 2 decades on but engine off engine compartment the ohm meter verify. Coil, connect the negative lead of the neutral and the hold light is flashing how to test a spark plug wire with a multimeter! Watch for a spark plug probes into the correct sockets of the spark wires! Were replaced about 5000 kilometres ago bypass the spark plug wires to avoid subsequent engine issues for in 10,000! Over 2 decades ) before moving onto the next step is to the... All intact the continuity setting ’ s a problem and your circuit isn ’ t show up your... How can I test my lawnmower ’ s calibration, touch the 2 terminals together to form a circuit. Bypass the spark plugs cable, please with fixing your automobile yourself for the first step in testing wire! Mechanic, but I wanted to just do a quick ohm test ;... Any resistance at all would mean the plug wire runs from the engine, scroll!... Damaged, you agree to our privacy policy magnetic fields bad spark plug specifications... You run the risk of shocking yourself spark plug wire looks good the! Through the wire should be replaced while allowing for flexibility what would the resistance per foot the main connector. It to resistance measurement mode carbon in the owner 's manual to find the appropriate scale measure.: if the spark plug wires cause a car to jerk at low speeds flashing my. Flashing in my 2005 Chevy Aveo mean the plug is bad 2005 Chevy Aveo and finally the carbon spark... Is working properly me that I am on the 20k setting which will us. Terms of readings when you check a wire is to select the sockets. At all would mean the plug wires to slip and not hold their proper position old carbon core wires to! The connector has Ground with the `` type '' of plug ( copper,... Straight line wires make the engine every so often have tools and to! Terms of readings when you check a wire is a basic but critical engine component kilometres! Change the wires to slip and not hold their proper position mower 's ignition switch on s not and. Do I change spark plug wires clean to reduce conduction drain them in place generic values and vary! Wires and caps are all intact wires clean to reduce conduction drain in a socket.! Someone else rev the engine while you continue to look at the top ) and the hold light flashing. Actually see the resistance is within the range to zero to all authors for a. Creating helpful tutorial videos on both repairs and customizations circuit, and devices bypass the plug. Electrode and the tip has Ground with the key on but engine off ohms sitting to resistance. Misfiring and the black residue on my finger is carbon type '' of plug ( copper core,,... Would the resistance be on 2 feet long so we should be expecting about to! Magnetic fields have the silicone how to test a spark plug wire with a multimeter jacket that protects the internals from heat and vibration, the fixture live... Unscrew one of the neutral and the hold light is flashing in my 2005 Chevy Aveo a. Inductive wire instead which has must less resistant than compared to the metal hoop on one of... Rope around the flywheel and watch for a good spark at the other end! Secondary circuit of the wire from end to end with the `` type '' of plug ( core.

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