Test Any Ignition Coil With A Multimeter! (Easy DIY Tutorial!)
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- เผยแพร่เมื่อ 31 พ.ค. 2024
- Tutorial on how to test ignition coils you’ll find when repairing your engines at home regardless of brand. Honda, Kohler, Stihl, Husqvarna, Briggs and Stratton - it doesn’t matter! With a multimeter in hand, you can follow along with this in-depth, step by step tutorial! I cover the entire process from start to finish including interpreting multimeter readings, pitfalls to avoid as well as revealing a crucial, often overlooked step that can cost you hundreds of dollars too. Learn how to account for variations in resistance values, ensuring an accurate diagnoses as well as gain insights into recognizing the signs and symptoms of failing ignition coils, helping you prevent miss diagnoses, unnecessary expense and time too!
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#multimeter #ignition #smallenginerepair #resistance #ignitioncoil #honda #briggsandstratton
00:00 Use a multiplier to test an ignition coil
00:51 What you need to test an ignition coil
01:00 What is an ignition coil?
01:33 Good resistance values of an ignition coil
03:15 How to test and ignition coil with a multimeter
05:44 Don't make this mistake when testing your ignition coil!
07:21 Reasons why you may not have spark
07:51 Symptoms to look for when diagnosing a spark fault
08:22 My favorite spark tester
![[Live สด] การออกรางวัลสลากกินแบ่งรัฐบาล งวดวันที่ 1 มิถุนายน 2567](http://i.ytimg.com/vi/3canzHC_d0k/mqdefault.jpg)
If this video helped you, please consider clicking on the THANKS button above to support my channel 🙌
Hey Tom, thank you for your work on these small engines, enjoy your delivery. Watched one of yours on carbs( I think?) recently. I am struggling with a leaf blower at the moment but also have a trimmer, a chainsaw, a snowblower and 2 mowers. All of these little engines run great for years but the 2 stroke ones seem to eventually get into more issues. The2 stroke blower has been shifting from issue to issue, surging (solved by carb rebuild), wierd running (partially solved by filing the new metering diaphragm tip to close to original ~0.60", came in at double that), starting and running issues especially when hot - partially solved by adjusting the carb screws, now every indication of no spark. Plugs new and old tested at 2 ohms each - ok, plug wet when trying to start( no spark?), kill wires and ignition permit switch test ok, new fuel, rebuilt carb, new fuel filter, air filter ok, etc, etc . Pulled the module and used your testing theme with my trusty Multimeter......secondary - plug wire to armature = 4.2Kohms.....slightly low but ok(?); primary - armature to kill tab = 148Kohms, plug wire to kill tab = 158Kohms. I assume the electronic stuff is hiding the 0.5 to 2.5 ohms of the primary. Awaiting delivery of a new module. Can not wait to test it. Any thoughts on the ~150Kohms readings? Keep up the excellent work, learning at Warp 9. Thanks Fred
I like the bottle brush tree in the background.
are these numbers the same with a 6 volt and a 12 volt coil?
I had my own workshop for 30 years and murphy was a constant companion so more often than not there was more than 1 problem or inconclusive. If I had a buck for every coil I tested that had good values but was crap....in the end I gave up these tests, it is only an indication ie if the coil is crap this will confirm it...or not. The most useful test (and fast) if the motor is running - but has an ignition problem - is to remove the cap from the coil and start the motor while holding (and being very careful) the end of the lead to the plug or earth if you have more than one cyl. The spark should be fat strong and blue and most importantly should easily be able to jump about 6mm. As you are holding the lead you can easily vary the distance and if the spark faulters and or the engine stops as soon as you increase the distance the slightest from the plug you know that either the coil is faulty or there is not enough power (dodgy electronics normaly wont let the engine run at all) - you have to then eliminate the plug first too of course but most often it is the coil. But if the spark and engine is still going strong with sparks an inch long you know the coil is not at fault. The next test is then the magneto coil (or with a battery ignition simply to measure the voltage at the coil - this will be pulsed if the electronics are not in the coil). Also here there is little point in measuring the resistance thru it as what makes these tests so inconclusive is a broken down insulation not bad enough to open or short it but just enough to allow moisture to get in. This then shorts it as soon as voltage builds up - same goes for the ignition coil. So you need a peak voltage meter which can be bought cheap and put in series on your multimeter. This then allows the multimeter to accurately measure the very short voltage spikes put out by the magneto and immediately shows up any problems with power supply as a high enough voltage of about 90 - 200v AC will not build up. You need to confirm those values depending on what bike/other you have as that is just from memory and I am retired now! There are also measuring charts for assessing the electronic parts but they can be hard to get right as they will vary depending on which multimeter you have. Sometimes all you can do to verify those is to employ a process of elimination. The best part of this vid was how he eliminated the TCI part of the coil from the test - well done. Hope this helps someone! All the best from Aotearoa
Thanks for watching and sharing 👍👍
Excellent comments especially about the blue 6mm long spark jumping from plug to earth. You are absolutely correct. Manufacturers tell us about blue thick spark.
Video author forgot air gap. If rust present it shorts magneto results in no spark. A failing plug sparks orange
@emanuelmifsud6754 Hey! Thanks for watching :) Though rust doesn’t affect the magnetism, it will affect the air gap clearance.
@@VintageEngineRepairs The air gap clearance is a very precise measure. Any variation to the recommended would result in the spark being deteriorated. It is essential to ensure the surfaces have no rust or loose rust. I have repaired these engines for 50years.
@emanuelmifsud6754 hi, the air gap doesn’t need to be overly precise, most people use business cards to set the gap, although I don’t, I use a a specifically made gauge. You have to be quite a way off to lose spark in my experience.
In this tutorial, you really nailed it.
I can take them, as you usually say, on points:
1) A coil can have good resistivity but in operation, the insulation resistance must be pierced - the multimeter applies a voltage of 9V and in operation the coil must support 15,000V. In conclusion, after measuring with a multimeter, it cannot always be eliminated as a problem.
2) As you say, a coil can be accompanied by electronic circuits. Which are of 2 types: analog and digital. They are already called ignition modules. The coil can be perfect, but the electronic part is defective, and then the measurements with the multimeter are fine, even though the module is defective.
The digital ones have a microprocessor and have an ignition map with advance angles corresponding to the revolutions and for the i500 also the injection times.
I can't mention them all here because a video would come out in letters...
Thanks for watching and commenting!
Thanks bud. This video is timed well because I've got a saw I believe has ignition issues. This is a big help. May God bless you and keep you.
That’s awesome, best of luck fixing your issue :)
A ignition issue could be as simple as a switch !
Some things you can not see completely through !
Faulty switches no doubt lead to the demise of barrels full of ignition coils and even whole machines !
Nice video Tom! Lots of great info. I need to watch this again.
Thanks Stella! Glad you enjoyed it :)
Probably the most informative and well explained i seen.
Thanks for the kind words!
Will tuck this one away for future reference. Thanks for all the info you provide for us.
Awesome! You’re welcome :)
Another great video Tom! I have been testing some Stihl coils and I was getting those weird readings. I’ll be sure to check them again.
Thanks for the kind words :) glad you found it useful!
Excellent video. That's more about an ignition coil I've heard from anyone. Thanks 😊
Awesome! Glad you enjoyed it :)
Good information well delivered. Thank you Tom. I will be referencing this video again and again. I bought a box of coils at auction dirt cheap. $20 for about 20 coils, mainly Briggs Quantum and Classic types by casual observation. I will be testing them to see which are keepers.
Amazing find!! I’m pleased for you, that’ll be handy. Glad you enjoyed the video :)
Awesome video, great explanation on how to test the coil and where to set the meter. Thanks
Glad it helped :)
Very comprehensive coverage on ignition coil testing - wish I had seen it years ago. I'm thinking I've thrown out many good ones based on faulty testing criteria. Cheers
Thanks for watching :)
I think that I have thanked you before, and if so, never mind !! Thanks Bro, I had this video saved ready for when I needed it, and today, I needed it, and now that I have actually done it, I will most likely remember it.... Thanks, again again....
Awesome! That’s great news :) you’re welcome!
Excellent explanation, I enjoy your channel. I have replaced several ignition coils this year for customers.
Thank you! Glad you enjoyed it :)
Nice job Tom, thanks for the explanation. 👍
Thanks for watching John! :)
Anytime bud
thank you for this information - I've saved it to my favorites
Awesome! Glad you enjoyed it!
Great video! Well explained and to the point!
Thank you :)
Electronics is definitely not my field of expertise. But you make it sound straight forward. Thanks.
Thank you!
Very helpful! Thank you!
You’re welcome!
Finally someone who knows what they are talking about !
Thanks for the kind words, glad you enjoyed it!
Great information Tom 👍
Thanks Nev!
Good explanation of HT coil
Thanks a lot
You’re welcome :)
Great video, very informative
Thanks Al!!
the best video out there...coils suck.
Thanks :)
awesome man thank you for sharing.
You’re welcome!
Superhelpful! Thanks
You’re welcome!
If a simple coil with no electronics, I have taken a 6-volt dry cell and hooked up a ground to the armature, hooked up a spark plug, and of course, ground it. Then briefly touch the positive connection and watch the spark plug and if it has a spark, it is probably good. Just don't hold the wire on the primary just touch it like a set of points are opening and closing.
Yes! You can do that :)
I saved this one Tom I want to give this a try ! Not good at the electrical side of small engine repair 🤷
Awesome :)
Brilliant many thanks
You’re welcome :)
Great video.
Thanks James!
Good video, good should help people
Thanks Bill!
Well done Mate!!☻
Thanks mate! Great to hear from you :)
Thank you!!!
You’re welcome! I hope it helps :)
Excellent
Thank you!
Very good video.
Thanks!
Good, thorough video, as always but I suspect I'll have to watch it multiple times to have a grasp. In the meantime, a quick question. I recently bought an older Echo chainsaw. The seller mentioned something about the coil, so I assumed it would be a spark problem, but starts right up and runs great. The problem is that the kill switch doesn't work. In true backyard mechanic fashion, I replaced the switch which was quite loose. That didn't fix the issue. Could a faulty ignition coil cause the problem I described? Thanks
Hmm very unlikely, it’s more likely a damaged wire mate. Get access to the coil and trace both wires to find the fault :)
One thing to note, I tested a coil on my Honda B16A2 engine. The readings were in spec but the engine wouldn't fire. I purchased a new coil after confirming the primary side trigger was switching. The engine fired up straight away after fitting the new coil.
Same goes for coil on plugs on my Yamaha R6, was misfiring at 12000rpm on track, the readings were in spec both hot and cold. I bought and fitted new coils, the bike now revved through 12k and onto 15k whilst accelerating.
You’re absolutely right! You can have coils that are within spec, but the electronics that control spark timing etc can be bad and that will cause a misfire or non sparking coil :) this is just one of the tests we can do, at home, to get an idea of a good or bad coil.
V clear and concise. Sorry to be dim but ref to Kill Switch or Tab I assume you are referring to the 12v feed from the Ignition Switch. Your comment re removing all corrosion off the mounting plate is v useful as I have taken the coil off my Quattro and treated the base plate with KuRust to neutralise the surface rust that was on it. Before all this the car fired now there is nothing coming from the main HT lead to distributor BUT I have a 12v feed from the ignition switch. Could this KuRust treatment be stopping the earth getting back to the car body? Thanks
Yes, certainly scuff the surface once you’ve given it the rust treatment, there is often a layer of oxidation or surface contamination. Scotch brite it :)
@@VintageEngineRepairs OK - Thanks for the v fast reply - appreciated
@@VintageEngineRepairs I just did the test on my Martindale AM5 Analog MM: Primary on Rx 10 scale shows 1 ie 10 Ohms. Secondary on Rx 1K scale shows 7,5 or 7500 Ohms. I am now trying to find the specification for the coil (resistance)
Thanks mate , I,ve got an 85 year old Villiers mk10 that is giving everybody mixed up with it absolute hell , bad compression despite valves being newly lapped in & gapped , ( bore belled out ) , no spark , previously severely butchered in a failed attempt to get an obscure flywheel off etc . I,ll use your method to test the coils , & go from there . Much obliged , & I,ve clicked the buttons .
Thanks Phillip, I restored a mk10, they’re an amazing machine. Solid, reliable, strong, well built! Good luck with yours!
Tom, I have been watching and re-watching your video on resistance values in small engine ignition modules, specically a 2 stroke module. The secondary measurements on my original module =4100 ohms, while the new module = 2600 ohms. The primary values original module = >30 Mohms ( fritzed?), new module = weird values depending on multimeter scale, 29.5Kohm to 201Kohm to 122 Kohm. I can not rationalize the electronic circuitry impact on the primary readings. Nether coil seems to create spark at my older plug and brand new plug. Any advice here?
Hey, did you remove all possible coating that may be on the coil armature giving you high readings? Remember that, as mentioned, the electronic circuitry on the primary side can affect the resistance readings you’re getting. Are these coils both Chinese clones? What machine is it on?
Can you add and electronic diagram of the coil spark plug the see all the components? Maybe there is a darlington transistor inside of the coil. Who power the darligton transistor base?
Hey; every coil is different and will have different circuitry. Best is to google the specific make and model of coil and see if you can get a cutaway or a schematic for it.
Hi. I’m struggling to be confident about which are the right testing points. I know which one the spark plug lead is. I have two cables connected other than the spark plug lead. One is green and one is black. Not sure which is the kill switch lead. Can you help identify the right connection points for testing?
I’m testing a coil for a 2022 Honda CRF 250R motocross bike.
I’d suggest downloading or getting a paper copy of a workshop manual, they’ll tell you step by step the process and readings :)
7:11 Pleas, Help me out here, ok so if you get inconsistent reading o the primary coil then proceed to a more accurate testing, which is testing the secondary winding:
HT lead to armature
HT lead to kill tab
When you said if the reading between the HT and armature are correct, but the reading between the HT and kill tab are incorrect that means the electronic components inside the coil are bad? Or just interfering and causing higher/different reading thus giving a false sign that the coil is bad?
So the most trusty test is between HT lead to amature?
Or both reading HT lead to armature and HT lead to kill tab have to be the same to finally say the coil is good?
Just interfering with your resistance. Secondary should always be between armature / ground and Ht, rather than the kill tab and Ht.
What is the bush/tree/plant behind you? I would like to get one if it would grow in my area. Thank you.
I believe it’s called a bottle brush, as for it’s Latin name I don’t know I’m afraid!
Thanks
Thank you for the super thanks Graham! Your support for the channel It’s really appreciated, I’m glad you enjoyed the video! :)
Is this only applicable with older units? I ask because I tested two brand new ones yesterday after watching this video. Secondary coil - 5.5k, primary coil 8.5 megaohms. After scouring the web someone said the circuitry in newer ones prevents an accurate reading of the primary.
It can do! Every coil is different, test both sides, check everything mentioned. Still no spark, replace coil.
Good video Tom. See you at work sometime buddy.
Hey Travis! Thanks mate :) much appreciated!
Well how do I know if the primary winding is bad or its internal electronics then if a high resistance could mean either is the case?
I mention it in the video, using both the hot side tab and the armature to check secondary. One will give high the other will give normal readings. If this is the case then it’s likely just the electronics.
My 2003 Honda XR400R service manual doesn't use resistance testing anymore. Instead Peak Voltage specs are listed which means you need an adapter for the multimeter.
Thanks for sharing 👍
Another excellent video! As you know, you can test resistor spark plug resistance too. :-)
Absolutely :) and the boots! Thanks for watching!
Ive just replaced a faulty coil on a 21HP B&S twin. The working coil has a secondary of about 6k Ohms, the other faulty coil has a resistance of around 3k Ohms.
Quite a difference! It’s interesting to see something like that :) glad you got it sorted!
I have an old Stihl 041 power saw with electronic Sweden ignition. there is also a German electronic ignition on some of them. And I have 3 parts saws I keep robbing electronic ignitions to keep the spark working. But one by one they fail over the years. There is a coil and it is attached to another part that picks up the magnetic signal from the flywheel. But these 2 parts are no longer available from Stihl. But all 3 coils test at around 1752 ohms which seems very high. Maybe you could test coils from an old 041 Stihl saw and show us how,,,,,,,,,,,,,,,I had to update to a 046 saw, but would like to get the 041 working again,,,,,,,,,,,,
Coils are generally very reliable, I believe the 041 is on points ignition isn’t it?
I have a briggs and stratton opposed twin 16.5 it ran good cut haft the lawn shut it off and would not start again tested coil says it's bad sence then I've tryed 6 coils on it and everyone of them went bad on the 3 attempt I disconnected all the wires to the motor except the starter cable still nothing have you ever heard of anything like this ?
I haven’t I’m afraid, but also I haven’t worked on one, are they genuine Briggs coils or aftermarket Chinese clones?
Is it possible the performance of a coil would be affected by heating up? Say after 20min of riding the bike?
Yes absolutely! When a coil is on its way out, they tend to present their issues when warm and run nicely when cold.
Thank you. I’m hoping that may solve my problem. My motocross bike runs perfectly well for 15-20 min then dramatically looses power. Sounds like it’s choking
Hey :) it could very well be ignition coil. There are other electronic components like stator windings and ecu’s that can also fail. If you get hold of the service manual, you can check the resistance values of each and find if any are out of specification. Hope this helps!
Hello Mate Will the cause the engine to start idle then when you raise the RPM it dies or hesitates then runs Hard to start when hot
Hmmmm possibly, it can be other symptoms too though! I’d suggest it’s more likely an air leak or scored piston. Have a look as the piston skirt through the exhaust port. It should be nice and clean, no scratches or vertical scoring!
@@VintageEngineRepairs Oh geez Don't jinx me Put a new OEM carburetor on it last season & ran great Occasionally would backfire thru the carburator when shut off It has spark but its faint It doesn't make a CRACK or POP sound its just real faint These small.engines are the devil
Nice video - thanks. What is the name of that beautiful red blooming tree behind you, and since it is blooming now, are you from Australia. Mike Ohio USA
Hey! Yes it’s summer in Australia right now :) I’m here, yes! It’s a bottle brush tree, isn’t it stunning! I couldn’t resist it as a backdrop:)
I am getting .389 on the primary is that close enough to .5 ?
Yeah that’s fine!
Good video, what is that plant behind you.
I’m not sure honestly! It’s so beautiful though I can’t resist using it as a back drop while it’s in flower :)
@@VintageEngineRepairs It's a Callistemon or common name Bottle Brush.
@treecycle4631 thank you :)
WoW
Glad you enjoyed it :)
Do you know what kind of tree that is behind you? It's gorgeous!
Bottle brush :)
Thank you! I was just watching videos about Multimeters, so I'll have to watch your video but those red flowers caught my eye first..@@VintageEngineRepairs
👍
Thanks!
👍👍
👍🤙
Buy a 500volt megger to check insulation breakdown resistance.
Thanks, I’ll look into it 👍
That won't help if you have a shorted turn in one of the windings, only if you have breakdown from one winding to the other or to the core.
You should also test the leads. resistence in leads ???
I did :)
This video is exactly why I prefer text-based information... don't have to weed through all the other garbage
What is that beautiful tree you are sitting under?
I think it’s called a bottle brush!
I stick the wires into the mains and if I see a spark I know it was good.
Into the mains?!
If anyone is wondering about the tree behind him it's a wallum bottlebrush... Anyways...
Haha everyone seems to be asking me, thanks for the clarification, it’s rather dull now we’re in autumn!
Great Aussie ‘bottle brush’
You didn't state what a normal reading between the kill terminal and HT terminal should be when checking for electronics.
There isn’t one
Maybe you can clarify. At 6:55 you are testing between the "kill tab" and the HT terminal. You then state "If the resistance value between the armature and the HT lead or barb is correct, but the resistance value between the kill switch or kill tab and the HT lead or the barb is incorrect, then you know that it's more than likely........" How do I know if the resistance value between the kill tab and the HT lead is incorrect?
@@wrench71 if it’s reading in the kohms or mohms like is shown 👍
what kind of tree is that behind you?
Bottle brush 👍
You completely disregarded secondary insulation breakdown. The secondary winding can and most times look normal, but at high voltage it breaks down. A multimeter will not show you if this is an issue.
If the insulation breaks down it will show a lower resistance value. Thanks for watching !
@@VintageEngineRepairs sorry, the insulation only breaks down at high voltage (flash over), not with the 2v applied with the meter in ohms.
Ohhh yes, ideally coils will be tested by running a high enough current through on a test stand. We can only work with what we have at home :)
@@VintageEngineRepairs
No, a shorted turn cannot be resolved by resistance measurements. A single shorted turn can make the coil non-functional.
A "ring test" will detect shorted turns, but it isn't something that is easy to do without more sophisticated equipment.
If you're married you can tell your wife to put her finger in the top of the spark plug and give the recoil starter a pull see what happens. You'll know if it has a good spark.. There's actually a spark tester you can buy very cheap. Sometimes a meter will show a good coil but it will have a voltage leak and arc internally or the spark is weak. Always check the distance between the coil and the flywheel. The correct distance should be the thickness of a business card. It's important to set the distance after removing a coil. While it's good to use a feeler gauge, a business card will work just fine.
Ha! I try and stay out of the dog house haha
Multimeters arent really accurate in the .5 ohm range. It could be a dead short and you would never know it.
It's better just to swap it out and see
Where did you hear about the accuracy?
This will not test insulation breakdown.
Thanks for watching
If you use multimeter 90% of the coils will check
Ok
It’s just one way to get an idea of the condition of them.
You sure don't sound aussie
I’m not
Looks like you only show how to test 2 stroke coil....
Hey, it's the same process for either.
more ,talk ,less ,Action,
Thanks for watching 👍
210224 Thank you mate
You’re welcome :) glad you enjoyed the video!
Thanks
Thank you for the super thanks! Always very appreciated ☺️