Operation and testing coil over plug ignition (4 wire) – Toyota/Lexus

okay we’ve got a 2003 toyota echo with a misfire trouble code and what i want to do with this one is walk you through how to check this for pin coil over plug design ignition system we can stay low-tech first and by low-tech what we can do is well of course will read the trouble code and I’ll get you a quick shot over at the scan tool it is a cylinder number for misfire detected Pio 304 so there’s your side of the code and what we want to do because this is a constant miss we can hear it we can feel it it was we can stay low-tech first and we’re going to do a cylinder drop test and make sure that we’re identifying the proper cylinder and if we are in fact dealing with the number four then we’ll go through the ignition checks on the number four cylinder of course there’s still compression and fuel you have to worry about but we’re going to start with the ignition okay so what I’m going to do on this design is I’m going to disconnect the coil and we’re going to listen for an RPM drop and then we’ll go from there so go ahead and start it up not sure if you can hear how this engines running it definitely has a dead myth I’m going to start with the number one just so you can hear it oh unplug this one here we get worse you got a broken bolt on this number three for this coil worry too much about that I’m going to go to the number four that’s what we have a code four unplug it no change whatsoever through the number brief you can hear it good RPM’s y’all know we do so here rpm drop soul 1 2 & 3 no rpm drop on number 4 guys shut that off okay so we know it is the number 4 cylinder that is misfired and what we found so far is that our scan tool and our trouble code is indicating the correct cylinder we always have to be careful with misfire trouble codes sometimes they identify wrong cylinders but we’ve got this we’ve got this correct and what we want to think about with the number 4 is is it spark is it fuel is it compression and there’s a lot of different ways that we can attack this vehicle one of the things that we can do is a clear flood mode crank and then listen to it to see if it has consistent compression sound I’ve shown this in other videos so we can do that real quick I’m going to unplug these coils and I’m going to have you crank this and we’re just going to listen to the way that this thing cranks as a sound test this would be basically a relative compression test that we’re doing go ahead and crank it keep cranking so I tell you okay good what I’m saying based on that sound is this is most likely not a compression problem so from there what we can do would be go after the injector or go after spark and I think for this video let’s go after the spark because we want to really emphasize how to check these four pin four wire coil over plug designs real quick word of caution when you’re doing so in a drop test like I just did where you’re unplugging ignition coils you’re going to set ignition coil primary circuit faults when you do that on most of these systems so be careful with that you know these are false trouble codes and these would be sensed off of the igf circuit that’s ignition confirmation signal that Toyota uses we’ll be talking about that as we go through this the computer is able to recognize by monitoring that circuit which coil has an open circuit with it so false trouble codes we set be careful with that okay couple of quick things that we can do with this if we don’t have a scope and and I’ve done this in other videos just to figure out if we have maybe a bad coil or about plug or if it’s an

injector problem there’s a lot of different directions we can go and I’ve shown some of them doing tailpipe emission test see if your eight C’s are high and there’s some variables with that you know the computer may shot the injector off we’re going to focus on the ignition system for this and one of the things that you can do would be to swap the coils and see if your rpm drop test moves if you’re dead cylinder moves with the coil then you know you have a coil problem you can do the same thing with the plugs for our purpose we’re going to focus on this number four I’m not going to do that I’ve already taken the bolt out and what I want to do is just start the car and do a simple output check of this coil to see if their spark on it and this is an acceptable method – there’s nothing wrong with this and again the difficult part is to show all the procedures on one car that’s just not possible and it makes for really a long video so we’re going to focus on the spark just have a test leg connected to ground and I’m going to hold it here and I’m looking for a spark to come out of this coil it’s that simple so go ahead and start that up okay the law and I have to be honest with you guys you’re watching this at a later time I already knew that this coil didn’t have spark but I wanted to show you the procedures that I went through previously this is what we did we moved coils around it moved with the coil we pulled the coil back out we did a spark output test of that coil and we knew there was no spark now the issue at hand here is going to be is there a control issue with this coil this is a four pin coil and on four pin designs and three pin design coil ever plug systems the transistors inside of here but our concern is the computer wiring the coil wiring and making sure that that is good before we replace the core so what I want to do first is I want to take you up to the board and we’re going to talk about the internal design with this and then we’re going to do some checks and see what we have and be able to make the call with a hundred percent certainty using the scope okay first thing that I want to share with you guys this is in section 22 of my book no start no spark diagnosis and this is on page 18 and I have a generic picture of a three wire pull this is a four wire but what I’m showing up here is a three one and the reason I have this picture drawn is to show you that there is a transistor that is inside of this coil itself there so there’s no external igniter there’s no external module it’s done inside of the coil itself the coiled primary is right here I’m not drawing the secondary in this picture to simplify it we’re just looking at a primary circuit and so with that here’s your positive feed coming in and then this circuit where the transistor is would be the ground side or the control side this is coil negative right here and this is coil positive when this transistor turns on this will connect this circuit to ground directly so one of the things with this design is you cannot view coil negative control voltage on most coils you would have a circuit that you have access to coil negative because you have an igniter a module a driver that’s external let’s call this the ICM this would be coil negative this is coil positive you can connect to scope here and view the coil negative control the voltage spikes the on/off control you can see on this design you cannot because coil negative is right here and this side of the transistor is the side that’s going to switch from high to low voltage when the driver turns on this side of it is a ground all time so you cannot see coil negative voltage on this design on four pin or three pin coils you cannot see coil negative voltage so if you want to see control you have to use an ant prep we want to know is this coil turning on or turning off we are limited what cannot do this but what we can do is measure with an amp clamp on either the feed side or well we don’t have this wire but we have this wire this ground we can measure

current flow on the ground we can measure current flow on the coil positive so either here or here would be one of the tests we good all right a little background noise and that last sex and an air hammer in the shot what I was saying is to measure control on this cut type of coil we can’t view call it negative voltage but there’s other things we can do we can measure our current flow here or here which will give us our current rad pattern we can do that another thing that can be done is the base circuit can be viewed for control from the computer and the way that this circuit works is the computer is going to send a small square wave on this circuit which is going to turn this transistor on and off every single one of these coil over plug designs with the transistor that’s inside you will see a square wave pattern on that one single one so that’s another method that we can use to tell us whether or not this color has control we have no spark we know that right our concern is our coil bat do we have a wiring problem or do we have a computer problem and if it went in the direction of a computer then we’d have to check inputs and things like that but it’s just a good direction test the next page that I have this is on this was a case study on a 2007 Honda Accord you can see that this control this red trace the square wave is what is hurting this coat on and off when the base circuit gets turned on you can see that is the exact time that our current increases through the primary circuit and when the base circuit is turned off is the exact time that our current flow stops so if we go back to this page and plug that in we have a square wave here that is occurring this square wave controls the base as this circuit is high we have current flow taking place when the circuit base circuit drops to no volts we turn the base off we current flow and these go hand in hand the grant for this coil would go hand-in-hand with the base circuit square wave that’s what I’m showing in this picture so we’re going to plug in these tests on this code so now you might be thinking what’s different about the four pin design 3 pin design 4 pin design this is the wiring diagram for this Toyota Echo you see we have four different coils you see each one has four wires are common wires would be the black and red this is the feed circuit you would need the rest of the diagram to see that it comes from the ignition switch actually so all of the coils share a power feed another shared circuit is going to be our ground which is our white black you can see all of these this splice here all of the grounds are shared if you refer to the other toyota echo case study that I have already up on YouTube where we had a bad computer ground bad block craft was it no communication issue this ground for these coils is in that location so the nice thing about working on the same car again is I know where that ground is how nice would it be to put my amp clamp here and measure all four coils I can do that principles of current flow we can measure the current from the primary circuit on all four of these quotes right here at this location if we choose to of course we can just focus on our number four if we want to as well that’s the one that has the issue so we have our common power we have our common ground what are these other two wires there’s another wire this yellow one that’s a common water and on the wiring diagram I don’t have the whole thing up here but I’ll just tell you what it says this yellow wire comes to the computer it says igf-i D F and then the single wire right here is the IG t for the number 4 IP t for the number this would be the IGT for the number-3 again i GT number two and so on i GT number one so we have our individual wires and really with that info you guys already know what the IGT wire is that

ITT wire is that little small square wave that turns the base of the transistor on inside of this coil this i GT wire would be in my generic diagram here this is off of a Honda but it would be a same thing this would be the IDT circuit computer this is my engine computer talking to the igniter or really controlling the base of the transistor inside of the quote that’s your IET circuit Toyota uses that abbreviation IG t IG t is ignition timing is where they get that radiation ignition timing IDT ignition timing the signal so the 4-pin the fourth wire is the IGF circuit that’s this yellow circuit IGF would be ignition conformation it’s a monitored circuit diagnostics for this is really no different than the three pin we still have a main power we still have a main ground and we still have a main timing signal and on/off square wave zero five volt zero four volt the difference would be the igf circuit now I can’t give you the internals of this but here’s what I know from monitoring these in the past when you have a primary field that collapses in in a coil we get a very large voltage but what’s inside of these coils is a circuit that creates a signal in response to that voltage spike and what it will look like if you were to look at say the ramp this would be the coil on this would be the coil off that’s where your voltage spikes going to occur in a secondary or in a primary pattern you see 12 like some kind of look like this to put voltage over the current you would have a primary pattern that might look something like this in this area this is where we get that collapse of the field that is where you’re I G that signal occurs you’re going to have a signal that will be a condition to square wave that occurs exactly where the spark occurs it creates a signal what’s computer use that for word for confirmation ignition confirmation that that coil just fired that’s what the IDF signals for okay now judging by our vehicle here and no spark in that number four coil shows you the limitations of the IDF circuit doesn’t it it’s not a perfect monitored circuit we have a problem with this coil yet we have no idea type trouble code we have no coil trouble cut that coil trouble code did not occur until I unplugged the court and then we saw a coil signal a trouble code for that coil because of no IGF signal now what you might be thinking of right now is how would the computer know if we’re sharing igf circuits how would the computer know which ones which think about this this computer is responsible there’s going to be some chip in here that’s going to be responsible for controlling the four coils it sends out that small square wave right so you got four different coils that are being fired at different times at at in fire motor sequence this would be the timing chip in here you’re going to turn this one on and off then this one then this one then this one and go in order so my question to you would be does the computer know which one it’s turning on and off take that tip and then run one say IDF signal coming in that IDF signal is also going to be staggered to isn’t it we’re not going to fire two coils at the same time so that IDF signal is going to be one two three four one two three four that signals coming back what’s the computer do it coordinates this one with this one and it wants to see them occur when this one turns off think about the square wave this is where coil primary begins this is where coil primary ends when does the spark occur when the primary stops so where is the igf signal take place if the computer sends this out it wants to see the igf signal occur right in line with this one what does that tell the

computer about that coil that’s good we don’t need for separate IDF sir it’s sharing the ideas okay one of the hard parts about doing this is to give you guys direction and what we can do and there isn’t one right way to do this I think that becomes more difficult as I continue to do this is to show a procedure and then alter that procedure and show you something else for this one I want to tell you where I’m going to go I’m going to choose the white black which is my ground wire for my amp plan we’re going to put our amp way up here so we’re going to watch our coil primary current on the ground side we could also use the power feed wire if we wanted to it would not make a difference whatsoever we can use either one current flow does not change if you go to this picture right here this generic picture if I have current flow coming through this coil winding on its way through the transistor to ground if you have six amps of current coming in you have six amps of current coming out yes voltage has dropped but current flow has not changed you can measure current here as easy as you can measure current here take your pick for what I’m doing for this video for no particular reason I’m going to pick the ground one the next thing that we want to look at would be this wire this IDT coming in that’s our base circuit now depending on what we have for this amp test we may not need to do that it’s as simple as this we have no spark on this coil right if we have a curve if we have a current ramp pattern doesn’t that tell you the computers base circuit control is working so we don’t necessarily have to show that but we’ll kind of overkill this a little bit for other situations you might encounter we’re okay maybe we don’t have a ram so what else do we do we’ll show all of the techs okay so we’re checking the amperage on the ground we’re also going to at the same time check this IDT circuit right here so I’m going to back probe this igt that’s our small square wave we’ll just do them both at the same time okay just a quick shot of my connections you see my amp clamp is on my white with a black and my voltage trace is going to be on my green with the yellow which is my control signal so let’s go up to the board again and see what they look like that go lights on no shop noises brutal sometimes all right scope I’m using is the Pico I haven’t hooked up already so let me go to my desktop open that up okay going to set my channels up this is the default you can actually set a default screen for this I don’t have one set channel a is my amp clamp I need to tell it what I’m using which probem using so I’m using my 60 amp clamp in the 20 amp mode and what that does is that’s going to set up my scales for me I’ll set it to a minus 5 to 10 amp scale there’s your amperage waveform on the screen and then my channel B is just going to be a simple voltage trace and so the normal probe the default is going to be volts and I’m going to set this I know it’s a 5 volt I’m going to set it to a 10 volt just to make the screen look good you can personal preference there it doesn’t matter it helps to know what you’re looking for you now get this a lot what scope settings should I use we’ll start the car get your signal and move things around them you’re not going to hurt it just be aware of your high voltage coils and injectors where you want to use an attenuator and everything else you’re pretty pretty good with time base I’m on a 50 millisecond screen right now that might be a little bit too fast to start with so I’m going to change that so we can see some repetition on the screen this is a 1 second screen that’s probably way too much but the nice thing with the pecos we can zoom in later on that picture so go ahead and start that we have a hose on this car okay I said that off for a second

I have my my AF crap was upside down I can actually invert it on here or I can go over to the car and flick my amp clamp which is what I’m going to do I’m going to start that back up again I was looking at this line to tell me that one of the reasons why I like to have screams I can tell what its inverted scales are off here these are thoughts references I can also in this was this air from the other coils that are all sharing the power beans and I can filter this but really right what this told us rain beer seven far gotta love the air hammers it’s the worst tool in the shop I hate that tool I’ve always hated that I hated more while filming right guys do we have enough information right here to tell us that we need an ignition coil do we have control our control is our amperage waveform here that’s the blue trace this is our current flow through the circuit and as I told you guys let’s go in on this just a little bit more get a little bit more detail here here as I told you guys this red trace which we can see is 0 to about 4 volts that’s pretty typical this is what I’m seeing across the board on coil ever plug the control circuit is 0 to 4 volt square wave that’s the computers control of this coil is the computer turning the coil on yes it is so how’s the computer it’s good how are the inputs can crank signals if this signal is here those are good too then we have an amperage waveform this thing’s upwards of 11 amps I don’t know if my if I see rode my probe properly here let’s take a quick measurement and that’s floating off to zero and then the top of that see what kind of number we got so we’re at eleven point nine four four or eleven point nine three our Delta between the two almost 12 bags that’s probably one of the highest current ramps I’ve seen on an ignition coil be curious to see what one of the other ones look like looks like maybe we should take a picture of that or what we can do is replace the coil and get a picture of the after sometimes aftermarket coils contains a characteristic though of the wave form so I think I want to look at one of the other ones as a point of reference and I think that’s where it would help to look at all four at the same time you can look at all remember I said originally that other ground all right there are certain faults in an ignition coil that you can’t see in a primary ramp and one of them is the secondary if it’s partially shorted or if it’s arcing somewhere else difficult to see sometimes with some of this stuff we look at I don’t know if this is going to be what the other ones look like or not I think if I remember doing this before they all look the same here’s what we know we know we need to pull it no question we have no spark we have good control is there a need to check the coil power or ground in this case and the answer is no because the amount of current flow that I have this is the highest current flow that I’ve seen on a cone so if I had a bad power background would net lower my average so I’m not worried about the power and ground check we need to pull it no question there’s an area right here that I’m focused on and I’m not seeing a turn on oscillation here and this is an indication of a secondary sort when you don’t see that now I could be wrong on this design that this is the way the other ones look but it doesn’t change the fact that this needs an ignition for I’m going to move these feeds to the solar next to it and we’ll take a look at what that would look like and we’ll throw the IGT set go in there – not that we need to look at that but just so you guys can see it I’m going to move to a

known good coin good pause that alright so I got this moved over to the number three and what we’re going to do with the number three is just compare what this area looks like right here to what that that number three looked like actually I probably should save this picture real quick let me do that okay can I get one you guys to start this we’ll see what this one looks like this is cylinder number three so it’s just on this area here to compare what we were looking at before and it’s subtle but there is a difference here if you look closely at that initial turn-on you will notice a difference here right in this area can you see it it was kind of a little straight up line on the other one and bridge looks about the same I’m about 12 amps of current but that issue right there that initial characteristic looks a little bit different pretty tough to pick that one out on this design let me throw in the igf signal here – we’ll look at that at the same time so can you start that back up for me again I already have it connected I just need to turn on my other channel okay pictures a little bit noisy but I’m not worried about filtering that right now there’s your IGF signal and I was I was incorrect in the location and where that thing actually is created this green trace is your IDF signal it is not charged by the collapsing field it must be charged by the current flow coming in I’m not sort of internal circuitry but this would be your IGF signal for the number-3 is it’s coordinated right with it and the other thing that you’ll notice with this picture is that our IGF is actually in my other channels too let’s just clean this up a little bit for viewing here on the camera notice that there’s your number three here’s your number three again and then you have an IDF signal all the way across so you have this is IGF IGF IGF that’s because it’s a shared circuit what’s creating those other ones there are other cylinders that are firing in here okay Heidi figt signals Toyota they’ve done this forever and again this is a known good coil that filtering has changed our characteristics here a little bit going to be careful filtering if you want detail all right we’re going to change that coil see what the new one looks like but really that’s pretty much good enough for us to call the coil replace the coil and I’ll get you a shot of the engine running running good after we’re done okay we got the coil Wayne we’re still going to we’re going to change the plugs and do the whole thing one coil change all the plugs but for now we just threw the coil in to get an aftershock go ahead and start the car for me please this area right here you can see what I mean no buy aftermarket coils what do we see with this aftermarket coil and as far as the characteristic of the ramp goes yeah it’s kind of goofy yup so we don’t want to read too much into that the other igf signals for the other cylinders they look pretty much like what we saw previously so there is a square wave with another little dip in here at our new coil while that has a really different look to it doesn’t it well the thing is is our misfire is gone and you can see maybe all right well you can see why in

after-market you can see Oh let’s get an average reading on this aftermarket coil 12.5 802 1/2 an empire current this is something to consider and I have a lot of issues with Nissan’s where people are changing coils and they’re not fixing the problem that you Nissan I believe is a 4-pin with an IDF circuit and the fix is to put factory coils in it so it’s just something to think about when you’re doing this you know characteristic differences between coil Rams that looks a lot different I’m going to do one more thing start this car back up I’m going to unplug one of the other coils once you have to pay attention to this igf circuit the green trace on one of the other cool i GF signal disappeared that is what looking at to know that there’s a problem with that foot a little different that cool back in are we going to worry about this idea they call looking different than this one I’m not going to worry about it as long as this quarter songs at a trouble code and it’s running properly definitely a different characteristic with that one more I’m going to get all the coils on the screen you can leave that role I’m just going to go I want to go to that calling feed that common ground so we can see the ball at the same time okay so now looking at this pattern now looking at this one I’m triggered off of this blue trace and you can see how the pattern is going to kind of change on us you see that what you need to understand when you’re looking at all four coils now then we’re going to change our triggers to make this better better view notice your controls or gets changing – you guys see that it’s kind of coming together if you wanted to focus that I talk now if you want to focus on only the number four what do you need to do change your triggers is something that you need to be – the number four and our trigger that you need to the number four is on the red trace so what we can do and change that channel B and then move this other some spice in there so that’s going to be a little difficult to see spike that’s triggering off of that spike going to be tough to pick that out maybe if I change my slope it’s better but there’s still some red spikes in here so we’re drawing some other pictures well the nice thing about the Pico let’s get a longer time base my sample rate so I’ll miss anything I’ll pause that picture there shut that off and now we can look at any of the ones we want to that IGF signal definitely looks different than the rest of these and I’m not saying that’s a problem but it is a good picture as to maybe why you don’t want to run an aftermarket coil so look at that look at that pattern that’s our this is our new coil this would be one that was in the car let’s do this we’ll look at all of it that’s our new coil that’s an existing coil another existing coil Gramps look

pretty pretty much the same there’s your fourth one so we’ve got three coils that look pretty good one that that doesn’t imagine you getting this car in with that different coil you would question that wouldn’t you if you had a misfire on that cylinder so just think about that it’s another variable hopefully that makes sense a little bit more on coil over plumbing how to test them what the igf circuit is what the IGT circuit is being confident and making the call no spark good control said we need a coil our misfire is gone I’ll get you one knocks out of the course you guys believe me that even though this picture we don’t like it and it could look better the ramps pretty goofy looking that our misfire is now gone and we do have spark so I’ll get you one more shot and we’ll end this stay left my connections in the screen so you can see where I was this is my coil control signal this is my IGF signal I haven’t put the bolt in for the coil yet you see where my amp clamp is now connected there is a main ground wire and it is down in this location it’s the same color see what gets you on that loop I think you can see it right between that rad hose right there there’s a white black ground wire that’s where I was I was able to measure all four coils from that location I’m just going to redo my cylinder drop test on the number four let you guys hear it take a listen so you see that we have a nice rpm change on that coil now that is a fix hope you guys like that you