Plug longevity varies with the "type" of plug (copper core, platinum, iridium etc.). 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. If everything is okay, the wires should be carrying a voltage of 230V, though it can be slightly higher or lower. This is important because as time goes on the LED, microcontroller, sensor, or whatever device being measured may change its power consumption (such as turning on an LED can resulting in a 20mA increase for a second, then decrease for a second when it turns off). Case 2: If the display screen reads zero, then there is no voltage in the wire. Test the wire from end to end with the leads of the meter. Do not assume that crossing spark plug wires is a bad sign. Look in the owner's manual to find the appropriate resistance for the wires. There are 11 references cited in this article, which can be found at the bottom of the page. Refer to the repair manual for import plug wire specifications. You can actually see the black residue on my finger is carbon. Attach the spark tester to the distributor end of the coil wire. This, my friend, is called a tune-up, and all cars need them every so often. 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. And finally the carbon impregnated fibreglass core, where the electricity flows. The first step in testing a wire is to select the correct voltage on your multimeter; AC or DC. 2. 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. If there is a complete circuit, your multimeter will either beep, show a “0”, or something other than a “1”. Step 2. Doing this will unhook the kill switch, ignition switch, and all the wiring associated with those switches. Mike Parra is a Master Mechanic in Arizona. Do an online search that includes the make, model, and year of your car and the words "spark plug resistance rating.". It is important to use a well-insulated screwdriver for this test. Then, pull the boot off of the spark plug and unscrew one of the wires at the end. If you have a manual for your vehicle, check there for the answer. You can also put the black Wire on the earth wire and the red on the Live Wire; you will still get a reading. The insulation stopping any voltage leaks. 3 years ago. Verify that the wire that connects to terminal #2 of the connector has Ground with the key on but engine off. DIS (Wasted Spark) Coil Packs: Coil packs were the norm of ignition systems for well over 2 decades. Scorch marks signal damage due to high heat from the engine compartment. Select the voltage (V) … Crack the engine and check for a good spark at the spark tester. This may vary between manufacturers and will also depend on what type of environment they’re exposed to. Connect your multimeter to the positive terminal or pin of your coil, and to the high output terminal that goes to the spark plug. I would. He is ASE (Automotive Service Excellence) certified, has an AA degree in Automotive Repair Technology, and has over 20 years of mechanic experience. Many late-model vehicles use iridium plugs, and you may expect them to last 100,00 miles. Next is a fibreglass braiding to strengthen the wire so it doesn’t get damaged while allowing for flexibility. Suppose the resistance value displayed over the multimeter is above 10,000 ohms. Test Speaker Wires with a Battery . It’s important to keep an eye on your spark plug wires to avoid subsequent engine issues. If the reading is … Have the positive lead of the multimeter connected into the metal hoop on one end of the spark plug wire. An absence of spark will require replacement of the spark plug. Have someone else rev the engine while you continue to look at it. ", 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. Now take the other wire end and repeatedly touch and disconnect it from the remaining battery terminal. The plug wire runs from the ignition coil to the plug cap. Results. If the spark plug wire looks good, the next step is to check for bad connections or bad switches. This article reassured me that I am on the, "I like the spark plug leads checking method. Spark plug wires have become nearly non-existent on many modern vehicles. Any resistance at all would mean the plug is bad. This article has been viewed 410,743 times. Can damaged spark plug wires cause a car to jerk at low speeds? A good spark plug should show an open circuit between the center electrode and the tip. Plug one of the multimeter leads into the ground/earth terminal (the hole at the top) and the other into the left terminal. Research source. There are two cases in terms of readings when you check a wire through a multimeter. By using our site, you agree to our. Pull the rope to spin the flywheel and watch for a spark on the original spark plug. Test for current by first turning off the power to the circuit. Feeling unproductive while working from home? If it still shows a “1”, then there’s a problem and your circuit isn’t complete. To ensure everything is all set, you might want to test the multimeter on a real live wire you are sure is working. I know there are other more definitive ways to test the wires but I wanted to just do a quick ohm test. 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. X We want to make sure that all the wires are connected correctly. Anyway, multimeter here I come. About: Car enthusiast YouTuber creating helpful tutorial videos on both repairs and customizations. Be sure to hit that SUBSCRIBE or FOLLOW button. Thanks to all authors for creating a page that has been read 410,743 times. If you really can’t stand to see another ad again, then please consider supporting our work with a contribution to wikiHow. Damaged clips may allow the wires to slip and not hold their proper position. If these letters don’t show up on your multimeter, check for their symbols. Before throwing away an appliance, test it with a multimeter. Setting the multimeter to the ohms sitting to measure resistance, on the 20k setting which will show us values in the 10,000 range. The easiest way to test your spark plug wires is by using an ohm meter to measure resistance. How do I change spark plug wires on a Chevy 2.2 engine? 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. You can also use a multimeter to test resistance. Do the same at the other end of the wire. Plug the red probe into the 10A jack. A digital multimeter is an indispensable tool for testing, diagnosing, and troubleshooting electrical circuits, components, and devices. 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. To test the continuity setting’s calibration, touch the 2 terminals together and hold them in place. Select "amps" on the dial. 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. Did you make this project? wikiHow is where trusted research and expert knowledge come together. Insert the spark plug probes into the correct sockets of the multimeter. If a spark is present, the problem is probably in the distributor cap, rotor or spark plug wires. Some manufacturers do this to cancel out magnetic fields. [1] Try inspecting the spark plugs and spark plug wires for problems while the engine is idling and then while someone revs the engine. How to test spark plug wires. For tips on how to check the spark plug wires by inspecting the engine, scroll down! Spark plug wires normally last to about 100,000 kilometres or 60,000 miles. Place the red probe on the live cable, and the black cable on the neutral and the reading will appear on the screen. Plug the black probe into the COM (common) port on your multimeter. % of people told us that this article helped them. Keep the spark plug wires clean to reduce conduction drain. We’ll start with a multimeter continuity test. Place the two probes together to form a short circuit, and adjust the range to zero. 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. 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. Individual coils for each cylinder that attach with a spark plug wire, similar to the LS motors used on Chevy and GMC trucks, can also follow this method. It’s not expensive and it ensures that that part of the car is good to go. Reply Testing an almost brand new wire, these were replaced about 5000 kilometres ago. This article was co-authored by Mike Parra. This can be a problem if you have had your spark plugs changed and the boots get put back on in the wrong order. If carbon tracking is present, the spark plug and the wire should be replaced. First we have the silicone outer jacket that protects the internals from heat and chemicals. Then, pull the boot off of the spark plug and unscrew one of the wires at the end. Check the reading on the multimeter. Mike Parra is a Master Mechanic in Arizona. 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. 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. Wipe the wire clean using a … Use the meter to verify that the resistance is within the range called for in the car's manual. 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. 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. Instead, hire a mechanic to test them for you. Get expert advice. If you can't reach the boot, use a set of spark plug wire pliers. Touch the metal parts of your terminals together to make sure it works. 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. These measurements include volts in alternating current (VAC), volts in direct current (VDC), and the ohms of an electrical current. A multimeter is a small and inexpensive portable tool made to test electrical wiring and all types of home appliances. Alternatively, you can find this end of the wire in a socket shape. 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. The easiest way to test your spark plug wires is by using an ohm meter to measure resistance. This wire is about 2 feet long so we should be expecting about 1300 to 2500 ohms. Step 5: Test the secondary circuit of the ignition coil. This article was co-authored by Mike Parra. Multimeter Test: Continuity. right path. Step 1. Therefore, it is always advisable you switch off the breaker on the signal that you are running the test on to avoid any possible severe damages. If the number on the multimeter is less than 1, then your multimeter is functioning correctly. What can I do? To do this, disconnect the main electrical connector coming out of the engine. It carries the high voltage (30k to 50k volts) produced by the ignition coil to the spark plug. 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":"