An ignition coil is a part of the engine that helps create the spark needed to start the car. It takes electricity from the battery and makes it strong enough to ignite the fuel.
The Nissan Versa is a small, affordable car that gets good gas mileage. The 2014 version has a 1.6-liter engine, which is pretty standard for a car of its size.
A battery cable is a wire that connects the car's battery to the rest of the car, helping to provide power to start the engine and run electrical parts.
Corrosion is when metal parts get damaged over time because of reactions with moisture or air, often making them rusty. This can cause problems in cars, especially with electrical connections.
The engine block is the big part of the engine that holds everything together, like the cylinders where fuel burns to make the car move. It's very important for how the engine works.
The GMC Sierra is another popular truck, similar to the Chevy Silverado, but often has more luxury features. It's also used for work and personal needs.
A misfire is when an engine doesn't work correctly, causing it to run rough or lose power. It can happen for different reasons, like problems with the spark plugs or fuel supply.
The Nissan Armada is a large SUV that can carry many passengers and their stuff, making it great for families or road trips. It has a strong engine and can tow heavy things like boats or trailers. People talk about it because it's a mix of being fancy and practical.
A five volt signal is a type of electrical signal that is used to control parts of the car's engine. It's like a small command that tells the engine what to do.
The secondary winding is a part of the ignition coil that helps create a high voltage spark. It has more coils of wire than the primary winding, which helps boost the voltage needed to start the engine.
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Hey, what's going on?
Automotive World.
Welcome to another episode of the Automotive Diagnostic Podcast.
My name's Sean Tipping.
I'll be your host once again for this week's episode.
Thank you so much for joining me today on the show.
I'm going to share something which you may be familiar with if you've been diagnosing
vehicles for a while is this is not exactly a new problem, but we ran into it just recently
and I've had it come through our diagnostic cases three times in the last couple of years.
So again, not super often.
I think I may have seen it once or twice prior to actually starting mobile, but there's
lots of documentation out there.
There's TSBs on some models.
It's documented within Identifix as well.
And this is Nissan and Infinity vehicles where the ignition coils melt, but not only do
they melt, they melt repeatedly.
So you either have the same coil or multiple coils on an engine, it's running.
So you do have some misfires, but eventually the little plastic coil over plug ignition coil
will just, you know, go nuclear and melt down and the plastic casing will crack.
And usually when this happens, it will blow a fuse, which not only supplies power to
the ignition coils, but also supplies power to the ECM.
And so you'll have an ECM that is no communication, you have a no crank, right?
And so that's the customer facing symptom that you're going to probably be getting into your
shop.
Again, maybe some misfires just to start, but this is the end result is you have a dead
vehicle, can't communicate to the ECM, put another fuse in, it blows, okay, find the
shorted coil, right?
And sometimes you can visually identify these things again, because they've melted down.
Sometimes you have to unplug the coil one at a time to see, okay, which one removes
the shorted ground on this circuit.
So we've seen this just this last week on a 2018 Nissan Armata, and that had the 5.6 V8 in it.
We've seen this on a 2007 Infiniti M35, it was either G or an M35, I don't remember
exactly which one, but it was a 3.5 liter V6 that had this same issue.
That one was actually towed to our shop, again, because of no communication to the ECM.
Actually, the reason that got brought to our shop is they wanted us to program an ECM for
it, because they thought it was failed.
And we identified that like, hey, we can't communicate with your used one, do you want
us to diagnose it?
And again, ended up being a fuse, and then the fuse was blowing because of a coil
that was shorted.
And then I also had a 2014 Nissan Versa with a 1.6 a couple of years ago with this exact
same problem.
Now, the reason I listed those vehicles off specifically is to point out that this is
not isolated to a single engine platform or model platform, right?
This is the V6 version, the 4-cylinder, the V8, and a span of at least 10 years,
I'm sure it's more, 2018 is definitely the newest that I've personally seen it on.
But what's happening here is the ignition coils are melting down repeatedly, right, and then
blowing the fuse.
But the question is, why is that happening?
And again, there's TSBs out there, you can probably find this.
And if you've diagnosed these, you've found this before, maybe this is helpful information
for you, though.
You haven't run into this.
Or maybe you have a Nissan or an Infiniti that's doing this, and it's not, you know, incredibly
common on that particular application.
So there's no documentation, there's no TSBs, it's not an Identifix for that one.
But it is for other Nissan's Infiniti's.
I mean, again, just Google it, you can find stuff on this.
What this is, is a excessive voltage drop to the engine block specifically, okay.
Now every single time that we've dealt with this, that is what it is.
And it usually ends up being the cable that goes between either the negative terminal
of the battery in the engine block, or in some cases it goes from the engine block
to the chassis.
That actually seems to be pretty common in the Nissan applications.
And there's voltage drop usually due to corrosion, but it can be a loose connection at the engine
block for the cable.
But either way, the voltage drop happens.
And what's interesting about this, and this kind of gets into the reason that I wanted
to bring it up on the podcast, I mean, obviously just making you aware of, hey, if you have
a melted coil on a Nissan, you should be doing a check to see if you have excessive
voltage drop on the ground side.
But I want to talk a little bit about the why, as far as I can decipher, there are probably
still a few elements where the next time I have one of these, I'm going to look at it
a little bit closer, because I have questions that are slightly unanswered.
But anyways, the voltage drop that occurs between the negative cable and the engine
block usually only ends up being a volt or two in my personal experience, okay.
So when I just did the other day, had two volts of drop, the Nissan I had documented had
1.5 volts of drop, and this is while the key is on, the engine is running, okay.
So this is not during cranking, which may be something that you want to check because
maybe the voltage drop is more excessive.
But here's one part of this that is interesting is that in none of these vehicles that
I have experienced, has there been a cranking issue as far as starting the vehicle?
So the voltage drop does not appear to be enough to cause a startability issue.
Now I'm not saying it couldn't, but again in the cases that I've dealt with, a no start
was not the, I should say a no crank due to voltage drop to the engine block did
not seem to be the issue, right.
These things started and ran if you had, you know, a fuse that wasn't blown in a coil that
had not yet melted down.
So there's a certain amount of voltage drop, but not enough voltage drop to cause a starter
failure.
Now, am I saying that that is not possible on a Nissan or an Infiniti?
Definitely not if the voltage drop or that corrosion or that loose cable gets to
be enough.
Of course you're going to have a problem cranking.
But in the cases that I've seen this, it's not that, right.
So it's a certain amount of voltage drop, but not enough to affect the starter.
Interestingly enough, right, you would think, I would think the highest current consumer
being the starter would be the first thing that's affected from something like this.
That would be my thought, right.
Even if it is, you know, two volts or whatever that that should be the thing
that is affected the most, but it does not appear to be that way.
The thing that ends up getting affected is the ignition coils.
Now how do these things melt down and what does it have to do with voltage drop on the
ground side to the engine block?
That was my question after I saw this one and I'm like, boy, I've had, you know,
a number of these.
And of course, yeah, like I say, it's well documented on Nissan Infiniti vehicles.
And then also why not on other vehicles, right.
I know for a fact, and I'm sure all of you do as well, that other vehicles experience
voltage drop on the ground side to the engine block.
Okay.
A Chevy Silverado for a perfect example.
There's probably more cases of, you know, the negative cables that you have to replace
on those Silverados than these Nissan's with the melted coils, meaning that I guess
there's a lot more Silverados on the road.
But it's a very common thing, yet I have never seen a COP coil on a Chevy Silverado or GMC
Sierra melt down like this.
Okay.
So it's not just as simple as saying, hey, if you have voltage drop here, that that's
going to affect the way your coils go.
So that was kind of a question of like, what is it about the Nissan's that this happens?
And why is it just with like a small amount of voltage drop relative, right?
There shouldn't be that voltage drop.
You should want to fix that.
That's an issue.
But again, not enough to affect the starter, but enough to affect whatever's happening
here and having coils melted.
So the Nissan Versa that I had looked at, this was the one that I think I spent the
most time diagnosing because I had not.
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The link is in the show notes actually ran into a situation like this prior to that.
Again, I think I fixed a few of them back when I was at Firestone, but I didn't really
do the testing to get there.
I didn't really do the full on diagnostics.
It was more of like, oh, here's a TSB.
Okay, let's do the TSB, which involved just cleaning ground cables.
There was no testing involved or anything like that.
This Nissan Verso was the first one that I've got my scope out and I'm really trying to figure
out because the guy called me is like, yeah, I've put in like five ignition coils on this
thing and they just keep melting down.
Eventually, it's not immediately.
It's not like you plug them in and they start smoking.
This is the vehicle start, the vehicle run, the customer will take it.
And then a few days later or a week later, they call up say, hey, you know, I've
either got a misfire or it doesn't start, whatever the situation might be.
And the coils melted again and it might be the same one.
It might be a different one.
And that's the thing is it's not always the exact same coil that melts down.
Sometimes it's a different coil.
So again, what's happening and why is it only affecting Nissan?
So what we've got going on because of the way that they set up the ground
connection again from either the negative cable or from the chassis and then run
it over to the engine block.
And then we have a cable where, again, it's loose or it's got corrosion on it.
You now have an elevated ground or you could even say you have a level of
voltage on the engine block in reference to the negative side of the battery, right?
If you're to take your meter, your scope, you put one end right on the negative
terminal of the battery and then you put the other lead on the metal block
of the engine while this thing is running, you'll measure 1.5 volts.
You measure two volts, okay?
So there is a voltage drop, but you actually have voltage.
You have an elevated ground on that engine block while this is happening, okay?
So that's one piece of it.
Now again, this can happen on other vehicles and manufacturers makes models.
Why does that not cause the same problem?
Now, this next part, I'm taking my best guess at this, but
I did look into it a little bit to see what could potentially make these
setups different.
And again, it's not like it's just one model, right?
Again, 07 Infinity, 14 versus 18 Armada, now all made by Nissan Infinity,
but different engines, different wiring diagrams, kind of sorta.
But you would think that if it's just some weird glitch with an ECM that
this happens when there's bad ground.
Okay, it's just that model does that, but this seems to persist across years and
across brands for these vehicles, which is what got me curious of what is
the same across these different applications that makes this problem
present itself in the same way repeatedly?
And so we have our, let's just say two volts on the engine block.
We have the elevated ground on the engine block.
Now I looked at all three of these vehicles, and
I can only attest to the ones that I've personally worked on.
And I know for sure that that was the problem.
I did the measurement, and I saw the fix, okay?
All three of these vehicles have the ground set up this way.
The ignition coils themselves, now I should point out that these ignition coils
are three wire coils, meaning they have a constant power,
a constant ground, and then a signal wire from the ECM,
which is switched to five volts in order for
the transistor in the coil to activate and actually complete the circuit.
It actually switches the ground to the primary coil, right?
Create a magnetic field that releases a class magnetic field.
You know how an ignition coil works.
But these are three wire coils and all of these ignition coils.
Across all three vehicles that I looked at, and
every other Nissan that I, I shouldn't say every other Nissan.
I looked at a few others, and they all seem to be set up this way.
That those ignition coils are grounded on the engine block.
That's an important piece of this.
Now, looking at the engine control module in all three of these vehicle applications,
the engine control module is grounded to chassis.
And I think that is part of what is going on here,
is that the ECM and the actual transistor in the coil or
the coil itself are referencing different grounds.
And I think this has something to do with what's happening.
Now, actually why these coils are melting down is,
and this is one application where I actually did the scoping was on the Versa.
The ECM appears to be activating it with a constant five volt signal on
that signal wire, which causes the coil to basically turn on and flow current.
Now on this Nissan, I got it to act up and
I was monitoring the signal to the coil at this point.
And normally you see a five volt pulse as the computer wants the coil to spark.
And at times it would hold this five volt signal to the coil even key on engine off.
Right, so it's not even getting a crankshaft signal, it's just that the key is on.
And the five volt is being held on this signal wire indefinitely.
And again, there's a transistor inside of the coil and
with that five volt on that wire, it is constantly sending ground to
the primary coil, it already has a constant power feed.
You're creating a heater with that thing that's just gonna eventually melt down,
which explains why they melt down, why they short, why they blow the fuse, right?
But that the five volt side of the control side of that ignition coils
actually staying active.
And although I didn't actually scope it on those other two vehicles that
I'm referencing, I have to assume the same thing is happening.
But then the question becomes, well, why?
And here's the other piece of it.
When you fix the ground, when you fix the ignition coil, right?
You put a new coil in it, and yeah, you can do a new spark plug if you want to.
Sometimes spark plugs cause ignition coils to fail,
I don't think that's what's happening here.
But anyway, besides the point, you fix what's going on with the vehicle.
You fix the ground, fix the coil, the ECM's fine in all these applications.
Now, we can point to Ford V6's that will have the coil melts,
and then you have a driver that's also failed in the ECM.
You have to replace the coils and the ECM.
That does not seem to be the case here.
I have not experienced that.
Now, of course, in those Fords, the ECM is handling the full amount of current
to the ignition coil, right?
It's a two wire coil, and the driver is handling a lot more current.
In these Nissan's, the driver in the ECM just has to send a little five-volt pulse
on that signal wire, and all the current actually happens
within the transistor of the coil.
It's a better setup because, you know, current equals heat,
which is going to wear components,
and you'd rather just replace a coil than an engine control module, obviously.
So it's definitely the better setup in regards to ECM longevity.
But again, I go back to, well, what's happening here
that doesn't seem to be present on other three wire applications.
And like I said, the five-volt signal seems to be pegged high
when this is happening, which, again, triggers the coil.
And my best guess on this just has to do with, number one,
how the ignition coil is wired up both externally and internally
and the circuitry within the ECM and how it drives that circuit.
Now, from what I could find, that circuit is actually driven high
and it's driven low in the ECM, meaning it not only pulls it up,
but it pulls it down to a ground.
And there has to be something going on where there is a difference
in the reference of ground between the engine control module.
Again, all three of these, it references chassis ground.
And then the coils, which, again, they're just transistors
and then coils of wire, there's not a logic chip within them,
but they are referenced to the engine block ground.
And something has to be happening here,
whether it be through the transistor itself inside of those coils
and the elevated ground on one side affecting the control side
or potentially even with the ignition itself,
whether that be on the primary or the secondary side,
causing something to happen on this ECM, on this control circuit.
And, again, I kind of dove into it, but I got in over my head
as far as, like, the transistor operation
and the internal circuitry of the engine control module.
And part of that is my understanding of it.
The other part of it is the inner workings
and exactly how it's set up on the board of that ECM.
You don't have a diagram for that.
That's proprietary information.
You'd have to take apart an ECM and look into it that way
to see, like, how exactly do they have this set up.
But there's something about how they have these coils set up
and that they have the ECM set up to drive this circuit
that this elevated ground on the block triggers this to happen.
But then the ECM does recover from it.
And it is a point I want to make is if you run into this,
again, from my experience,
you don't have to worry about the ECM being damaged.
You fix the other stuff and it's good to go.
Just make sure that you don't have that elevated ground
on the block.
The one other interesting thing that I did notice
looking at the wiring diagrams on these things
was if you go way back to an episode I did
with Fonslow and Skundrich,
I think I may even brought it up on an episode
with just Fonslow, but we were talking about
ignition coil wiring and looking at the secondary side
specifically and how the secondary winding,
you know, the opposite end
that is not connected to the spark plug
is wired up to positive, right?
So you have a positive feed into the coil
and then the secondary winding is connected to that.
And if you think about the secondary ignition circuit
as a complete circuit, it's like,
well, it has to go through the battery then, right?
From engine block to the battery through the battery
and then to the positive side to complete the circuit.
And we talked about that at length in those two episodes.
So I won't rehash all of that.
I did talk to a few people after the episode,
including Paul Danerks, he had had the same question
and the best explanation that I got
is that the battery acts as a form of like a capacitor
and you have to think of the secondary spark
more like AC voltage, even though it's technically not,
it's acting in the same manner that AC voltage would
and that some manufacturers will do this to reduce,
you know, the electrical noise that you would have otherwise
if you wired up the secondary to the ground side.
Now, I realize if you don't have a diagram in front of you
you might be like, what the hell are you talking about
right now, Sean?
But you can go back to one of those episodes.
I'll see if I can link it in the show notes
and you can basically hear my questioning of it
from a fourth grader perspective,
which that's sometimes that's the best way
to ask questions about things.
Anyways, anyways, all of these Nissan coils
are set up that way, which I found interesting enough.
Does that have something to do with it?
I don't know, might just be a coincidence.
But again, what's curious is they seem to set up
all of these ones in the same manner.
So there was something to do with how the coils
are grounded to the engine block,
how the ECM is grounded to the chassis
and how these circuits for the coils work, right?
The way the ECM drives that circuit up and down
and that the transistor in the coil provides a ground
to the primary winding.
If it applied a power, would this be completely different
because the transistor would have to be completely different
the way it's set up, maybe, right?
This was all what I looked into to just answer the question,
well, why don't we see this on other vehicles
that have corrosion on the ground side to the engine block?
So I think it has to be a unique set of circumstances
that Nissan was just, you know,
they were smart enough to figure that out,
but we do see it, it's something that happens
and some of this is just more curiosity than anything.
It's not really gonna help me fix any more cars
if I know exactly why it happens, but it's interesting
and I ask myself questions like that
when I'm out there diagnosing cars.
So maybe you do too
and maybe that's why you're listening to this podcast.
So if you have any experiences with one of these things
or you have more information on the internal circuitry
or maybe if you get one of these in your bay
and you got a PicoScope
and you wanna do some testing, get a hold of me
and I'll be like, hey, check this,
what does this look like
or how does this present itself?
The next one I get that I have some more time
to spend on, I think I actually will just again,
for curiosity, but that's all I got for today.
Hopefully you've found that interesting or helpful.
Like thank everybody out there for listening,
all the feedback and all the people
I've gotten to talk to.
Always appreciate that, so keep it coming.
Let me know if you got ideas or thoughts for the show.
Other than that, let's all get out there
and start fixing the world one car at a time.
(*y Outro Music*)
About this episode
Nissan and Infiniti vehicles are facing a recurring issue with ignition coils melting down, leading to misfires and ultimately a no-communication scenario with the ECM. The episode dives into the diagnostic process, revealing that excessive voltage drop to the engine block is often the culprit, typically caused by corroded or loose ground connections. Host Sean Tipping shares real-life cases, discusses the implications of voltage drop, and raises questions about why this problem seems unique to these brands compared to others. Insights into effective diagnostic strategies are also provided.
This week on the show I share an issue that I've seen on several Nissan/ Infiniti vehicles were the ignition coils repeatably melt down, causing a no start. We'll address the root cause and speculate a little on the "why" behind this brand specific fault. See this episode for my first discussion on secondary windings that are wired to the positive side of the electrical system.
