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How do i test the ignition coil to know if its good or bad

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Mike Sullivan

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Easiest way without a meter or 12VDC tester, then simply pull coil wire out, insert screwdriver into distributor hole where coil wire was, then hold coil wire with pliers and have someone turn over engine while you hold coil wire close to screwdriver blade and look for a spark to ark from coil wire, if you see spark jump, coil is good, but only if it is healthy spark. If you have a meter, you can check to see that you are getting 12VDC to positive side of coil, most have red wire or plus sign at terminal depending on model and make.

Posted on Feb 05, 2015


Ray Brauer

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With the vehicle in 'Park'[Auto] or 'Neutral' and hand brake on [Manual], open the bonnet and locate the ignition coil.
1. Ensure the lead is fully engaged [and that all wiring connections are tightened and free from dirt and corrosion] then follow it to the distributor cap and check that the other end is properly connected and the plug leads are also.
2. Remove a spark plug lead at the plug then remove the plug.
3. Connect the removed plug to it's lead and while holding the threaded portion of the plug in positive contact with bare metal on the engine [exhaust manifold] have someone turn the ignition key to crank the engine.
WARNING: Be careful if the engine is hot and wear gloves and use pliers with insulated handles when holding the test plug.
4. As the engine is turning over inspect the spark plug electrodes for any sign of sparking. A blue spark is what you want to see. Orange spark or none at all is bad news for the coil which needs to be replaced.
5. When you're done, replace everything properly, account for all tools and remember a clean engine is a serviceable engine. how do i test the ignition coil to know if its goo - 25325059-xy42b42qawgpyeebopf3rzcc-3-0.jpg

Posted on Dec 16, 2014



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There are a couple of ways to test it. First if you have a multi meter set it on ohms and see if you have continuity. You can also try using a 9 volt battery with two leads going across the primary coil. You will have to touch the leads for only a half second and if it is working you will see a spark from the high voltage output if there is a wire going from it to ground but make sure that they are not directly connected just very close to each other

Posted on Dec 16, 2014

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Hey Travis,
From experience.. this sounds like a ignition coil going bad... you can get them tested at any GOOD motorcycle dealership.. We used to test for the other shops in town,,(Yamaha has/had something called an "electrotester" that will measure spark travel and put a load on the coil...we would wrap the coil in rags to get them hot when we tested them) If its bad, it will show up

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P0351 code loss of power 2.3L08ford ranger,it warms slow and really need to eliminate1~voltage regulator is where?) & 2~ ground through PCM) 3~knowing limits&threashholds{sensorsIGNcircuit}?Ty 0$

P0351 loss of power ? That's not what this code is about . P0351 - Ignition Coil A Primary/Secondary Circuit ,you have a bad coil and possibly a bad coil driver inside the PCM . Do yourself a favor an take your vehicle to a qualified repair shop !
P0351 - Ignition Coil A Primary/Secondary Circuit Description: See the description for DTC P0350. Possible Causes: See the possible causes for DTC P0350. Diagnostic Aids: See the diagnostic aids for DTC P0350. Application Key On Engine Off Key On Engine Running Continuous Memory Coil-on-plug (COP) ignition testing - GO to Pinpoint Test JF . GO to Pinpoint Test JF . Coil pack ignition testing - GO to Pinpoint Test JE . GO to Pinpoint Test JE .
P0350 - Ignition Coil Primary/Secondary Circuit Description: Each ignition primary circuit is continuously monitored. The test fails when the powertrain control module (PCM) does not receive a valid ignition diagnostic monitor (IDM) pulse signal from the ignition module (integrated in the PCM). Possible Causes:
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Diagnostic Aids: Use the 12-volt non-powered test lamp to verify START/RUN voltage at the ignition coil harness connector.
Check the coil driver circuit for open, short to VPWR, or short to ground. Application Key On Engine Off Key On Engine Running Continuous Memory All GO to Pinpoint Test JE .

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1983 oldsmobile cutlass supreme,wont start

Well, you know the ignition coil has to be good. then the ignition control module inside the distributor has to be good. It controls the ignition coil firing times. This module can be tested at a parts store. And then, also in the distributor and attached to the ICM is the pick-up coil which tells the computer crankshaft position, so the computer knows when to signal the Ignition Control Module that it is to cause spark out of the coil. These are the components of the ignition system, so you know how to check them. Ignition coil, ICM, pick-up coil, and the pcm, computer.

First, check that power is getting to the coil when the key is turned to on. The coil must have battery voltage applied to it before it can cause spark. If there is power there, test the ignition coil, test the ICM, then the pick-up coil. If your wiring is good, one of them components may have failed. And of course, the last thing to suspect is the computer, the pcm. Hope you don't have to get that far.

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Do you have fuel, is your fuel pump working. If you do not have any spark at all, have you been able to check to see if you have power to your distributor. If so and you do have some then it might be either your ignition coil, pick up coil or your ignition control module. Your pick up coil in in your distributor under the plate. The coil is on top of the distributor cap. The ignition module is right under the cap where all your distributor wires connect to. Some part houses can test your ignition module and let you know if good or bad. Good luck.

Mar 22, 2014 | 1992 GMC Sierra K1500

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No spark 2 coil &distributer

Do you mean no spark from the coil or distributor? Because the coil needs battery voltage to it to operate.
If you have no spark from the coil wire and you believe the wire is good or you have no reason to suspect it failing in a very short time, then before you do anything else, you should check if the small, pink wire to the little + side of the coil is a live wire (has current or voltage, and the connection is clean and tight) when the key is in on position. If no power there, the ignition switch or the wiring from the switch to the coil is bad.
If you have power to the coil, then either the coil or the electronic ignition module (inside the distributor, I think) may be bad. They can both be tested. Auto parts stores will test the ignition module for free. There are other possibilities for no spark, like a computer fault, or a bad pick-up coil, or a wiring or grounding fault, but for starters test the coil or swap in a known good one. If not the coil, check the ignition module next.
Good luck. Don't see many of those cars on the road anymore. Hope you keep it running.

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2 Answers

Please I need help. I have a,1995 geo prizm. I have replaced the fuel pump, fuel filter, fuel pu relay switch, temp sensor. Took it to a shop and hooked up to machine for check engine light and found out...

It's not really a switch. Below is a desciption of what the code means. In about 50 percent of the cases it's a bad connection which is causing the failure and there are many tests to check different circuits. In order to rule out the ignitor here is a quick test you can do. Below is a picture of a breakdown of you distributor (yes the ignitor is in the distributor). Take the distributor cap off. Using a digtal volt meter check with your postive probe the black wire terminal connected to the ignition coil and ground the negative probe to a good grouns like the battery. Make sure you are getting at least 10 to 12 volts. If you are check the connection at the brown and black wire between the coil and the ignitor and make sure all is good (like good continuity) If all is good, chances are the ignitor is faulty. If you are not getting the voltage on the first test right at the black wire terminal at the coil the coil could be faulty. As I said it's a 50/50 thing on this code as far as wiring or a componant such as the coil or ignittor. I have found in the past that in most cases if say a coil or ignitor goes bad, it's just bad and you end up in a no start situation but there are those odd cases that outside temps effect everything like engine heat or a componant over heating.Hope this helps and good luck.



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2 Answers

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Sep 08, 2011 | 1999 Plymouth Breeze

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There is no spark at the spark plugs and tahoe wont start

First check power to the coil. Pull the connector off and probe the connector terminal from the pink wire with a 12 volt test light. Connect the test light clip to a ground point/bolt on the engine. The test light should come on when the ignition switch is on. If not, suspect the ECM-1 fuse is bad or the ignition switch is bad.
If there is power to the coil, next test the coil. Run a jumper from the battery positive terminal to the pink terminal on the coil itself. Pull the coil wire off the distributor and place the wire close (within 1/4 inch) to a ground point on the engine. Then, briefly touch a jumper from the black/white coil terminal to engine ground. The coil should release a spark. If not, replace the coil.
If the coil is good, suspect the crankshaft position sensor is bad or loose. I'm assuming your engine light is off, but the sensor can fail without setting the engine light. If the engine light is on, see if you can get a scan to see if a crankshaft sensor trouble code is set.
Please let me know if you have any questions.


Nov 03, 2010 | 1997 Chevrolet Tahoe

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I have a 92 Honda accord that has been sitting idle for a long time and now wont start. Ignition lights are on and engine turns over but there is no spark from the coil to the distributor. I changed the...

Do not hotwire the "-" terminal on the coil. The ignition system modulates the "-" signal to release the sparks. Check the ignition fuse under the dashboard. If good, use a test light at the coil to check for voltage at the coil. If you don't have a test light, you can buy one at a parts store for a few dollars. Connect the test light clamp to engine ground and touch the point to the "+" terminal of the coil. If no voltage, suspect the ignition switch is bad. If there is voltage at the coil, suspect the ignition module is bad. If you have more questions, please let us know.

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1 Answer

Is it unusual to have all eight ignition coils go bad at once. Is it complicated to replace them on your own. How do you test each coil to see if it is bad? Thank you

The easiest and cheapest way is to go to a shop wherethey use scopemeter testing.

The DIYer's way is to get the shop manual buy a spark tester and do exactly what the manual and the testers manual tell you to do to measure for spark.

Another DIYer's way is to buy a coil pack and swap it out for a bad one and then test for spark.

Not likely that all coils went. Ignition module is a common for all coils and so is battery and ignition switch.let me know how you make out.

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