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Discussion Starter · #61 ·
other than that i sincerely thank everybody for all your help you gave me, i just dont know what else to do anymore. im still open to any tips for now. But i may just be out of a vehicle completely now, i dont know. i dont know what else to do. I cant believe how crazy this problem ended up being.
 

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And when you say I proved that its the connector.....youre talking about the connector that actually plugs into the coil pack? You think that little connector is the problem?? I mean the connector plugs in? You think the one terminal on that connector just went bad??
Yes. That is exactly what I think. In fact, I think everything fine is fine up to and including the Yellow/Red wire going into the connector and then things go wrong where the terminal is broken and it does not connect to the coil pack pin.

It is not the coil pack or its pins because you checked it (and besides, it is brand new).
It is not the Yellow/Red wire because the PCM seems to pull the line to the ground properly.
So what else could it be but the connector that makes the PCM think there is a fault in the coil B primary circuit?

It still could be that it is the output transistor behind pin 52 of the PCM (the driver as Automender said) that, although it is able to let the test light blink, is not able to create enough of a current through coil B, but I would only go that route after I made 100% sure there is no connection problem. I would even go so far as to cut off the connector and solder the 4 wires straight onto their 4 pins of the coilpack before I would even consider replacing the PCM.
 

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other than that i sincerely thank everybody for all your help you gave me, i just dont know what else to do anymore. im still open to any tips for now. But i may just be out of a vehicle completely now, i dont know. i dont know what else to do. I cant believe how crazy this problem ended up being.
Here is an option, G7 Computers

Seems reasonable but never used them. If it were me I would buy the cheapest coil off of amazon, ebay or junkyard to do a final test it isn't the coil. Check the resistance by probing at the coil connector to the pins of the PCM connector. I would check the resistance of the problem cylinder's plug wires because there can be bad wires out of the box. I know you may have done these before but I would redo it just to be sure. Other than that it seems like a driver problem in the PCM but it doesn't seem 100%.

Also I would just because it is me, I would use jumpers with alligator clips and connect the common power wire and the suspected driver circuit to the pins to your old coil but to a known internal coil to see if you get a spark without any plug wires connected. That would convince me it is a PCM driver issue or primary wire but checking the resistance should eliminate the wire.
 

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Yes. That is exactly what I think. In fact, I think everything fine is fine up to and including the Yellow/Red wire going into the connector and then things go wrong where the terminal is broken and it does not connect to the coil pack pin.

It is not the coil pack or its pins because you checked it (and besides, it is brand new).
It is not the Yellow/Red wire because the PCM seems to pull the line to the ground properly.
So what else could it be but the connector that makes the PCM think there is a fault in the coil B primary circuit?

It still could be that it is the output transistor behind pin 52 of the PCM (the driver as Automender said) that, although it is able to let the test light blink, is not able to create enough of a current through coil B, but I would only go that route after I made 100% sure there is no connection problem. I would even go so far as to cut off the connector and solder the 4 wires straight onto their 4 pins of the coilpack before I would even consider replacing the PCM.
Agree with your statement except I would get a connector from a Pull a Part junk yard for a few bucks and just cut and solder it on the your harness.
 

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Agree with your statement except I would get a connector from a Pull a Part junk yard for a few bucks and just cut and solder it on the your harness.
Yes, if only because a new connector is surprisingly expensive (the cheapest is $25).

And indeed, it allows you to change coils if you want: interchange 2 of the three wires (by resoldering them) and interchange the corresponding spark plug wires accordingly.
 

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Yes, if only because a new connector is surprisingly expensive (the cheapest is $25).

And indeed, it allows you to change coils if you want: interchange 2 of the three wires (by resoldering them) and interchange the corresponding spark plug wires accordingly.
That would seem to be the ultimate way to rule out the connector, sparkplug wires/plugs and coil but there still maybe a weak current path somewhere in the wire, connector to PCM and ultimately the PCM. What if the wire strands were breaking slowly and finally got down to a few left but not enough to carry the current needed to strongly fire the coil but enough for the test light. Or even the PCM female or male connector had some corrosion and limiting current. I have a clamp on DC current meter that could be quick enough to measure current flow but maybe a cheap multimeter which usually has a ten amp limit could be placed in series to measure the flow.
 

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Discussion Starter · #67 ·
Yes. That is exactly what I think. In fact, I think everything fine is fine up to and including the Yellow/Red wire going into the connector and then things go wrong where the terminal is broken and it does not connect to the coil pack pin.

It is not the coil pack or its pins because you checked it (and besides, it is brand new).
It is not the Yellow/Red wire because the PCM seems to pull the line to the ground properly.
So what else could it be but the connector that makes the PCM think there is a fault in the coil B primary circuit?

It still could be that it is the output transistor behind pin 52 of the PCM (the driver as Automender said) that, although it is able to let the test light blink, is not able to create enough of a current through coil B, but I would only go that route after I made 100% sure there is no connection problem. I would even go so far as to cut off the connector and solder the 4 wires straight onto their 4 pins of the coilpack before I would even consider replacing the PCM.
Thats true. I would just find it so crazy for one of these seemingly fine terminals on that connector to be bad. Ive sprayed it down with electrical cleaner and it looks perfectlly fine. But i guess it could be bad. Oh yeah, i forgot to say that I did a few ohm tests on the connector terminals and measured them all to ground while it was disconnected from coil and all the terminals had the same reading except obviously the 12v common terminal. But i guesss that still doesnt verify the wires 100%. I will try a new connector as well i suppose.
 

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Discussion Starter · #68 ·
Here is an option, G7 Computers

Seems reasonable but never used them. If it were me I would buy the cheapest coil off of amazon, ebay or junkyard to do a final test it isn't the coil. Check the resistance by probing at the coil connector to the pins of the PCM connector. I would check the resistance of the problem cylinder's plug wires because there can be bad wires out of the box. I know you may have done these before but I would redo it just to be sure. Other than that it seems like a driver problem in the PCM but it doesn't seem 100%.

Also I would just because it is me, I would use jumpers with alligator clips and connect the common power wire and the suspected driver circuit to the pins to your old coil but to a known internal coil to see if you get a spark without any plug wires connected. That would convince me it is a PCM driver issue or primary wire but checking the resistance should eliminate the wire.
yes i have checked the resistance of the plugs and wires but i guess it cant hurt to check again.

Im thinking about cutting all the loons open and stuff and really taking a look at the Problem Wire from coil pack to PCM and retesting everything - seeing if theirs any breaks or anything. Idk. But im pretty sure i absolutely have to figure this out now. Because i just got off phone with Ford dealership and its $600 for a PCM from them! not including programming or anything. So even if the PCM is bad, i cant get a new one. Also the guy on the phone at Ford said he really doubted it was the PCM and that they dont have problems with them usually. So idk may have just been service talk. Im at the point where now im just gonna have to replace the connector and all wiring and dont leave a trace of doubt that its anything but PCM
 

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I find it extremely unlikely that the wiring internal to the protective cover is damaged but in your case it may seem possible. Have you ever pulled the PCM connector off of the PCM and inspected the pins and do a resistance check from PCM pin to female coil connector pin?

Here is another link to Ebay but you need your vin number to get the new computer if needed. Engine Computer Programmed with Keys 2006 Ford Taurus 5F1A-12A650-GE GSF4 | eBay

Just saw this but have viewed it completely.
 

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After looking at the video and you don't have a hard short to ground to drain your battery I am starting to think the issue is a wiring resistance issue or a faulty coil. If you have a clamp on DC current meter or multmeter that can handle the current flow of the primary circuit you could see and compare the amps to each coil. You would have to cut the wire to place the meter in series to measure. Most meters can handle 10 amps in current and have fuses to protect them.
 

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He makes an interesting remark in the video when he says the PCM connector is upside down compared with the documentation in

2006 PCM pinout

Although he is himself confused as to where pin 25 exactly is, he is probably right, because in the video there is no wire at the upper-right pin. So that must be pin 104. So the three wires underneath it must be the three pins 78, 52 and 26 for the coils. The two that you can see clearly, surely look yellow to me.

So I think I have to correct my earlier post. The three pins are not at the passenger side but, conveniently, at the driver side.
 

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Updated the post above and for reference here again:

The PCM pins for the coils A, B and C are all three at the very end of the PCM connector. Since the PCM is installed upside down compared to the pinout documentation, these pins are at the driver's side of the connector, so we have:

PCM pin 26 = bottom row, last pin = coil A = Yellow + Black stripe = circuit 850 = P0351 trouble code = cylinders 1 and 5
PCM pin 52 = second row from the bottom, last pin = coil B = Yellow + Red stripe = circuit 851 = P0352 trouble code = cylinders 3 and 4
PCM pin 78 = third row from the bottom, last pin = coil C = Yellow + White stripe = circuit 852 = P0353 trouble code = cylinders 2 and 6 = middle coil of the coilpack.

and the firing order of the Vulcan is 1-4-2-5-3-6 which translates into coils A-B-C-A-B-C.
 

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Since you are about to replace the connector anyway, you might already cut the Yellow/Red wire (not too short to the connector, so you can strip it) and check whether there is 12V on that wire that it should get from coil B. My assumption up till now is there isn't and that the 12V you saw before on the backprobed wire came from a pull-up resistor in the PCM.
 

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Discussion Starter · #75 ·
I find it extremely unlikely that the wiring internal to the protective cover is damaged but in your case it may seem possible. Have you ever pulled the PCM connector off of the PCM and inspected the pins and do a resistance check from PCM pin to female coil connector pin?

Here is another link to Ebay but you need your vin number to get the new computer if needed. Engine Computer Programmed with Keys 2006 Ford Taurus 5F1A-12A650-GE GSF4 | eBay

Just saw this but have viewed it completely.
Yes, ive pulled the PCM off a few times now and inspected everything, dont see any corrosion/damage/bent pins/or anything. I also sprayed the connector down with electronic cleaner. I have checked for voltage at the PCM for the ignition coil wires, i do have 12v there when the key is on. I also tested the resistance from PCM connector to the coil pack connector and it checked out good.

As far as that youtube video goes, i have actually watched that one several times now, I also caught onto the terminals being backwardds before I ever checked my PCM the first time luckily. I also was able to verify i was testing the correct wires on the PCM because its clean enough that I can see the numberings of the terminals. Ive went to this video because he also has the same OBD codes as i do.
 

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Discussion Starter · #76 ·
Updated the post above and for reference here again:

The PCM pins for the coils A, B and C are all three at the very end of the PCM connector. Since the PCM is installed upside down compared to the pinout documentation, these pins are at the driver's side of the connector, so we have:

PCM pin 26 = bottom row, last pin = coil A = Yellow + Black stripe = circuit 850 = P0351 trouble code = cylinders 1 and 5
PCM pin 52 = second row from the bottom, last pin = coil B = Yellow + Red stripe = circuit 851 = P0352 trouble code = cylinders 3 and 4
PCM pin 78 = third row from the bottom, last pin = coil C = Yellow + White stripe = circuit 852 = P0353 trouble code = cylinders 2 and 6 = middle coil of the coilpack.

and the firing order of the Vulcan is 1-4-2-5-3-6 which translates into coils A-B-C-A-B-C.
Yes i caught onto the PCM being backwards as ive seen that same youtube video a few times now in my research. You are correct the pins are on the driver side of the PCM.

Im out doing some testing now, so the voltage the coil pack leads get with the key on is just from the 12v common circuit i think. Because i just tried unplugging the coil pack connector and THEN turning the key to the ON position and i lost voltage to all 3 leads but still had voltage on the common. But when you plug it in, they all share voltage. Is it safe to try to crank the engine with the coil pack connector unpluged or would it not even do anything? i want to test the 3 lead wires while cranking the engine (with fuel pump fuse unplugged) so i can see if they are doing what theyre supposed to when not connected to the coil pack. I do have a multimeter with a 10 or 15amp fuse, but im kinda worried i will screw something up and leave my car completely undriveable if i start cutting too many wires.
Its just hard right now because I have to drive myself to the doctor 4 times a week. So when i start messing with wires, i just have to make sure i have enough time to put it back together so i can limp the car down the road the next day. I know driving it like this is terrible but i have no choice right now.

And i hopefully am supposed to be getting a little bit more money in a couple days so i am gonna first replace the connector and the wiring or whatever and then everything will be new except the PCM. and i guess that would tell me whether its PCM or not?
 

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Discussion Starter · #77 ·
Since you are about to replace the connector anyway, you might already cut the Yellow/Red wire (not too short to the connector, so you can strip it) and check whether there is 12V on that wire that it should get from coil B. My assumption up till now is there isn't and that the 12V you saw before on the backprobed wire came from a pull-up resistor in the PCM.
Yes i was just saying in another post, i just tested the coil pack connector leads again with it UNPLUGGEd from coil pack and i turned the key on. and none of the leads have 12v in this instance, only the common wire has 12v, Which i guess makes sense. But when you plug the connector into the coil pack, all of the wires have 12v.
 

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Yes i was just saying in another post, i just tested the coil pack connector leads again with it UNPLUGGEd from coil pack and i turned the key on. and none of the leads have 12v in this instance, only the common wire has 12v, Which i guess makes sense. But when you plug the connector into the coil pack, all of the wires have 12v.
There goes my theory. So now Automender's strategy is best.

Also I would just because it is me, I would use jumpers with alligator clips and connect the common power wire and the suspected driver circuit to the pins to your old coil but to a known internal coil to see if you get a spark without any plug wires connected. That would convince me it is a PCM driver issue or primary wire but checking the resistance should eliminate the wire.
Hopefully you can backprobe pin 52 and thus install your own wire from the PCM to the pin for the middle coil (bypassing the connector). Normally the secondary of that coil produces a clear spark for 2 and 6. Install a wire from the battery plus to the common pin. Install your test light and check it is blinking like before when you crank the engine, indicating your new wire is properly connected to pin 52. Take out the test light (to be sure) and crank the engine again. Is there is spark from towers 2 and 6 (test with the spark plug wire 3 or 4)? If not, things do not look good for your PCM.

One other thing: is the radio noise capacitor still attached? Sounds superstitious, but perhaps you can unground it to take it out of the equation.
 

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It does seem like a faulty PCM driver for that coil. I have programmed keys into my PCM using the normal method of having two programmed keys but you can't use that method to add your keys to a new PCM that has other keys programmed into it. They question is what is better or cheaper to have the old one repaired or buy a new one with two keys uncut but preprogrammed.

You can use Forscan to program keys into a PCM but it is the paid versIon at least a free trial of the paid version. I have not done this but others on the forum have.
 
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