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Ignition coils burn when you crank the vehicle

Tiny
MALLYBOY
  • MEMBER
  • 2006 INFINITI FX35
  • 3.5L
  • V6
  • 2WD
  • AUTOMATIC
  • 98,764 MILES
This vehicle burns all the cylinder ignition coils when you crank it, I first diagnosed it and there was no fault code stored. Then I unplug the ignition coil connector to check resistance on terminal 3 and 2 (power and ground) with ignition switch on, there was no resistance. Then I checked terminal 1 and 2 (igniter from ECM and ground) there was resistance or short to voltage. Could this be an ECM issue or wire problem? Though I suspect wire problem.
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Tuesday, May 24th, 2022 AT 7:16 PM

16 Replies

Tiny
KASEKENNY
  • MECHANIC
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Normally the ECM driver is what gets fried when the coil is shorted.

So, if you are finding all the coils shorted then we have a larger issue that would most likely be a wiring issue on the voltage supply from the ECM. These are the only wires that are in common for each of the coils.

https://www.2carpros.com/articles/how-to-check-wiring

Please let me know if I am not understanding but if I am then I agree with what you are thinking.

Thanks
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Wednesday, May 25th, 2022 AT 7:28 PM
Tiny
JACOBANDNICKOLAS
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Hi,

I have a few questions. I check them differently, and it is likely you already know the answers. At each coil, there will be a white wire with a blue tracer. Each one should have power when the key is on. Do you have that?

Next, each coil has a black wire which is ground. Do you have continuity to ground via that wire at each coil?

The remaining wire will be a different color for each coil. These run to the PCM.

I need to know if you are getting power to the white/blue wire with key on.

Let me know.

I attached a pic below of the wiring schematic for your reference.

Take care,

Joe

See pics below.
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Wednesday, May 25th, 2022 AT 7:30 PM
Tiny
MALLYBOY
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  • 309 POSTS
I need to know if you are getting power to the white/blue wire with key on? Yes, this is the power source to the ignition coil through ECM Relay. I first used multimeter set to DC MODE and I unplug ignition coil connector to read voltage, and it was 12volts, I also used test lamp probing one lead on the terminal 2 of ignition coil connector and other lead on the terminal 3 of ignition coil connector with ignition switch on, and it illuminate brightly. Then I used multimeter probing the negative lead on the same terminal 2 of ignition coil connector and positive lead on terminal 1(igniter ECM) of ignition coil connector, and it reads 05volts. Now I set the multimeter to Resistance Mode to trace short to voltage, I probe the positive lead to terminal 3 of ignition coil connector. And negative lead to terminal 2 of the same connector, the multimeter did not make beeping sound. Immediately I removed the positive lead from terminal 3 and put to terminal 1 leaving the negative lead on terminal 2(ground), the multimeter begins to make beeping sound. Then I checked from the schematic diagram if there is connection between terminal 1 and 2 i.E igniter wire from ECM and ground, I did not see. At this point I suspect that the igniter wire and ground are bridged causing resistance on the wire and also burning the coils when cranked.
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Friday, May 27th, 2022 AT 1:05 AM
Tiny
JACOBANDNICKOLAS
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Hi,

When you checked the ground to the ECM, did you have someone crank the engine? The ECM will only provide a ground path at certain times.

Let me know.

Joe
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Saturday, May 28th, 2022 AT 8:34 PM
Tiny
MALLYBOY
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When you checked the ground to the ECM, did you have someone crank the engine? No,
I want to ask, if I want to use Test lamp to check if the ECM is grounding the coil, how do I probe ignition coil connector, is it by probing Test lamp lead to terminal 1 and the other to terminal 3 or to terminal 2 and 1 of ignition coil connector while cranking the engine and then looking at test lamp to see if there will be a spark-pulse, just the same way injector is being tested using test lamp?
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Sunday, May 29th, 2022 AT 1:30 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

Terminals 1 and 3. Terminal 3 is power (should have 12v at all times with the key on and terminal 1 should provide the ground path via the PCM. If you have no power at pin3, you could even run the test light direct to the battery positive (B+) and then probe terminal 1 for ground. But the engine must be cranked to see if you are getting a ground path. You will need a helper.

Let me know what you find or if I can help.

Take care,

Joe
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Sunday, May 29th, 2022 AT 7:25 PM
Tiny
MALLYBOY
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I want to ask again, is it normal that resistance should exist between terminal 1 and 2 of ignition connector? Because when I checked, resistance did not exist between terminal 3 and 1, terminal 3 and 2, but only exist between terminal 1 and 2, which I did not see any connected link from the electrical diagram of these circuit, that's why I suspect initially that terminals 1 and 2 are bridged causing coil burning.
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Monday, May 30th, 2022 AT 12:46 AM
Tiny
KASEKENNY
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Just to jump back in on this. Are you finding this on all the coils or just one?

I am attaching the coil testing below that has this detail in it but the best thing to do is check another coil, assuming this is just one coil doing it. Checking another cylinder that does not have this issue is the best way to compare what is normal or not.
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Monday, May 30th, 2022 AT 6:56 AM
Tiny
MALLYBOY
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Just to jump back in on this. Are you finding this on all the coils or just one? I am finding it on all the coils connector terminal 1 and 2. If it is normal, what is causing the coil burn, is it the ECM? Why I disagree with the ECM is that when I check voltage on terminal 1, it reads 5volts, which is normal volts for grounding sensors but let me check the spark test first using test lamp to see if it will burst the lamp.
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Monday, May 30th, 2022 AT 11:27 PM
Tiny
KASEKENNY
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When you check voltage on terminal 1 you are getting 5-volts? The signal wire from the ECM? This is the wire that interrupts the 12-volt feed to create the high voltage spike.

I am attaching the OEM diagram that will help with this, but 5-volts seems high.

This chart is showing that at idle you will have about.2-volts. So, if you have 5-volts then that would explain why the coils are failing.
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Tuesday, May 31st, 2022 AT 5:20 PM
Tiny
MALLYBOY
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When you check voltage on terminal one you are getting 5-volts? Yes. This is where I think the Signal wire is interrupting the ground wire since there's resistance and again if the 5-volts is not normal, then it should be the ECM since it is the signal source unless wire are shorting somewhere causing the 5-volts.
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Friday, June 3rd, 2022 AT 3:32 AM
Tiny
KASEKENNY
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Exactly correct. I have not checked the voltage on one of these vehicles before, so I don't know if the 5 volts to be normal or not but going by what the testing shows that is too much.

I have a 2006 Nissan and they are basically the same so I will go out tomorrow and check the voltage coming from the PCM and see what that is giving.
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Friday, June 3rd, 2022 AT 6:30 PM
Tiny
MALLYBOY
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I have a 2006 Nissan and they are basically the same so I will go out tomorrow and check the voltage coming from the PCM and see what that is giving.
Please try I am waiting for your response.
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Saturday, June 4th, 2022 AT 2:02 PM
Tiny
KASEKENNY
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Just to be sure you are back probing this circuit and you are getting 5 volts when cranking the engine and the coil connected?

I had the engine running and it was a 3.5L Nissan (basically the same) and the max voltage I had was.127 volts. Which would be in line with what the testing above shows. So, if you are getting 5 volts then that is what is burning up your coils.
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Saturday, June 4th, 2022 AT 4:07 PM
Tiny
MALLYBOY
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The max voltage I had was.127 volts. I do not understand, did you mean 127v or 1.27-volts?
If the 5-volts are burning up the coils, what is the solution?
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Sunday, June 5th, 2022 AT 12:05 AM
Tiny
KASEKENNY
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No. The max voltage I was getting was

.127 volts

Meaning 127 millivolts

The spec was 2 tenths of a volt. See the attached document.

If you are getting 5 volts then that is more then 25 times higher then what it should be.

This means the PCM is sending 5 volts rather then the correct voltage which should be around.2 volts.

Did you back probe the connector with it plugged into the coil and test this while you were cranking the engine?

Unless you are testing this incorrectly which is giving incorrect readings, it looks like the PCM is the issue.
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Sunday, June 5th, 2022 AT 8:52 AM

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