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  #1  
Old 09-23-2018, 04:23 PM
jlaguardia jlaguardia is offline
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'92 SVX burning out ignition modules?

I've had a '92 SVX for 8 years or so and fixed a bunch of relatively simple issues over the years, but now I have a bug that I can't find an explanation for. I searched this forum but couldn't find this exact issue. What happens is the car begins to misfire at cruising RPMs (and higher) - it will idle OK and I can usually limp it home. If I turn it off and try to restart it, it will crank but not restart. I had a similar problem once with another car, and took a guess and replaced the ignition module that's bolted to the firewall with a used one on eBAY, and that seemed to fix it - for a while. After a few drives, same thing happened again with the second module. I looked around and found some forums (not SVX) saying that ignition modules in cars of this era can be damaged by bad coils somehow "feeding back" into them. So I bought all-new coils ($$$), and found another used ignition module, and again everything seemed fine for a couple of drives. Then it happened again - rough at high RPMs, limped it home, and now crank with no start. Has this "burning out" of ignition modules happened to anyone else?
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Old 09-23-2018, 06:24 PM
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Re: '92 SVX burning out ignition modules?

Quote:
Originally Posted by jlaguardia View Post
I've had a '92 SVX for 8 years or so and fixed a bunch of relatively simple issues over the years, but now I have a bug that I can't find an explanation for. I searched this forum but couldn't find this exact issue. What happens is the car begins to misfire at cruising RPMs (and higher) - it will idle OK and I can usually limp it home. If I turn it off and try to restart it, it will crank but not restart. I had a similar problem once with another car, and took a guess and replaced the ignition module that's bolted to the firewall with a used one on eBAY, and that seemed to fix it - for a while. After a few drives, same thing happened again with the second module. I looked around and found some forums (not SVX) saying that ignition modules in cars of this era can be damaged by bad coils somehow "feeding back" into them. So I bought all-new coils ($$$), and found another used ignition module, and again everything seemed fine for a couple of drives. Then it happened again - rough at high RPMs, limped it home, and now crank with no start. Has this "burning out" of ignition modules happened to anyone else?
I think that is called the igniter that your describing bolted to the center of the firewall under the hood.
I have had my car for 10 years and still have the original igniter and coil on plugs, I would guess its something else causing the problem
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Old 09-23-2018, 07:05 PM
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Re: '92 SVX burning out ignition modules?

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Originally Posted by 92 SVX View Post
I think that is called the igniter that your describing bolted to the center of the firewall under the hood.
I have had my car for 10 years and still have the original igniter and coil on plugs, I would guess its something else causing the problem
It actually sounds to me to be more of a short of some kind than anything else.

Might want to detail check all those lines for pinching to ensure that none of them are bare anywhere. Maybe a line hanging too close to an exhaust, or even the intake which does get very hot sometimes.
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  #4  
Old 09-23-2018, 08:05 PM
jlaguardia jlaguardia is offline
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Re: '92 SVX burning out ignition modules?

Yes, the "igniter" or "ignition module" or "ignition control unit" is the thing that I've been replacing. Although the problem certainly can be due to something else that is damaging the igniter, please note that the igniter is, in fact, being damaged. For example, after I bought the new coils, I tried the new coils with the first two igniters I had on hand, and the car did not start. I then swapped in the "new" (used, from eBay, but new for this car) igniter and the car ran fine for a few drives, then failed again. This tells me that something (if not the coils, then what?) is "burning out" or otherwise damaging the igniter. Any ideas as to what that might be? I will certainly check again for some sort of "short" - although I'm not sure how that would damage the igniter.
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Old 09-24-2018, 12:38 AM
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Re: '92 SVX burning out ignition modules?

Quote:
Originally Posted by jlaguardia View Post
Yes, the "igniter" or "ignition module" or "ignition control unit" is the thing that I've been replacing. Although the problem certainly can be due to something else that is damaging the igniter, please note that the igniter is, in fact, being damaged. For example, after I bought the new coils, I tried the new coils with the first two igniters I had on hand, and the car did not start. I then swapped in the "new" (used, from eBay, but new for this car) igniter and the car ran fine for a few drives, then failed again. This tells me that something (if not the coils, then what?) is "burning out" or otherwise damaging the igniter. Any ideas as to what that might be? I will certainly check again for some sort of "short" - although I'm not sure how that would damage the igniter.
The ignition coils draw a relatively heavy current which is beyond the the switching capacity of the ECU. The "igniter" comprises what amounts to a set of solid state relays, each switched by a low current signal from the ECU and in turn, switch the high current required to energies each of the coils.

The igniter is supplied with current via the battery circuit and if this fails the igniter can not supply current to the coils. This circuit although not likely, could be intermittent.

A short circuit to ground in any of the wires connecting the coils, or a short at a coil connection, or within a faulty coil will overload and damage a power transistor within the igniter.

A direct short circuit would normally immediately destroy a transistor, but your fault appears to take time to develop. Something must move or be affected by heat. Check for something foreign around the coils.

Even though unlikely, also check for possible open circuit in a plug wire, or connection which might cause a intermittent on/off situation thus causing a nasty voltage spike back to the igniter.

Do you have a multi meter and know how to use the resistance ranges?
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Old 09-25-2018, 02:55 PM
jlaguardia jlaguardia is offline
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Re: '92 SVX burning out ignition modules?

AHA! Thanks for the info, Trevor - something like what you're describing is probably the gremlin. I'll check all the wires as carefully as I can - I thought I did so when I put all the new coils on with the most recent igniter, but of course I could have missed something. I have a multimeter - what do you suggest I check? If there is a procedure already described in a previous post that you know of, just point me at it.

Given the time and money already spent on this, I was Googling around for alternatives, and found some guys who upgraded their Impreza-WRXs to new-fangled coil packs that have the igniters right on the coils. This takes the old-style igniter away, but requires some re-wiring of the harness to the new-style coil packs. I think I could figure out how to change their 4-cylinder wiring diagram into a 6-cylinder one. Has anyone tried this on an SVX? Here is the link:
https://forums.nasioc.com/forums/sho....php?t=1192028
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Old 09-25-2018, 07:11 PM
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Re: '92 SVX burning out ignition modules?

Quote:
Originally Posted by jlaguardia View Post
AHA! Thanks for the info, Trevor - something like what you're describing is probably the gremlin. I'll check all the wires as carefully as I can - I thought I did so when I put all the new coils on with the most recent igniter, but of course I could have missed something. I have a multimeter - what do you suggest I check? If there is a procedure already described in a previous post that you know of, just point me at it.

Given the time and money already spent on this, I was Googling around for alternatives, and found some guys who upgraded their Impreza-WRXs to new-fangled coil packs that have the igniters right on the coils. This takes the old-style igniter away, but requires some re-wiring of the harness to the new-style coil packs. I think I could figure out how to change their 4-cylinder wiring diagram into a 6-cylinder one. Has anyone tried this on an SVX? Here is the link:
https://forums.nasioc.com/forums/sho....php?t=1192028
“something like what you're describing is probably the gremlin” You show that you are on the right track and appreciate that an intermittent fault represents a real challenge. The proper approach its to locate the problem rather than follow the expensive route of replacing all and sundry.

I no longer have an SVX and after four years forget some of the physical details involved in respect of plug connectors and the like, therefore take this into account.

First off disconnect the 8 pin pug/socket connector in the cable running from the igniter to the coils. Measure the resistance between sockets 4,1,7 and socket 3. Also between 5,2,8 and 6. That is between the wiring going to the coils and I am depending on a diagram in this respect.

Set your meter for the lowest available ohms reading and the readings should fall between 0.7 and 0.85 ohms, taking into account the connecting wire resistance. Make sure you do not touch the probe ends as your body will record a reading. If you are using a digital meter, connect the probe ends together and note the resistance of the included probe leads so that this can be deducted and allowed for within the tested circuit.

If possible make secure connections to the sockets by wedging in the meter probe tips so that you can wriggle the wiring to the coils about while a reading is registered in order to detect an intermittent situation, i.e. connection, wire or coil winding.

Next, using the highest ohms reeding, test all pin outs for a possible short circuit to ground, again while moving things about.

Report the results and we can move on with the diagnosis. You have a curly one which will test your patience, and mine. LOL

PS It would have been best to carry out these tests with a hot engine but I gather yours is NBG.
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Last edited by Trevor; 09-25-2018 at 07:27 PM. Reason: PS added.
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Old 09-26-2018, 06:28 AM
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Re: '92 SVX burning out ignition modules?

Check to be sure your alternator isn't over charging
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Old 09-26-2018, 02:48 PM
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Re: '92 SVX burning out ignition modules?

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Check to be sure your alternator isn't over charging
Yes Hucck, something well worth keeping in mind. However the solid state items involved are fairly roust but that does not mean that they are absolutely immune in respect of voltage spikes.

Therefore this poses a question to be answered. Has anything else electrical failed or become troublesome, over the period that the problem has existed?
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Old 09-27-2018, 05:14 AM
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Re: '92 SVX burning out ignition modules?

Quote:
Originally Posted by Trevor View Post
Yes Hucck, something well worth keeping in mind. However the solid state items involved are fairly roust but that does not mean that they are absolutely immune in respect of voltage spikes.

Therefore this poses a question to be answered. Has anything else electrical failed or become troublesome, over the period that the problem has existed?
I only mentioned it because I had a 2000 Moto Guzzi Jackel, that fried 3 ECU's before I realized it was over charging (and ECU's for a Guzzi aren't cheap!)
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Old 09-30-2018, 11:12 PM
jlaguardia jlaguardia is offline
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Re: '92 SVX burning out ignition modules?

Quote:
Originally Posted by Trevor View Post
“something like what you're describing is probably the gremlin” You show that you are on the right track and appreciate that an intermittent fault represents a real challenge. The proper approach its to locate the problem rather than follow the expensive route of replacing all and sundry.

I no longer have an SVX and after four years forget some of the physical details involved in respect of plug connectors and the like, therefore take this into account.

First off disconnect the 8 pin pug/socket connector in the cable running from the igniter to the coils. Measure the resistance between sockets 4,1,7 and socket 3. Also between 5,2,8 and 6. That is between the wiring going to the coils and I am depending on a diagram in this respect.

Set your meter for the lowest available ohms reading and the readings should fall between 0.7 and 0.85 ohms, taking into account the connecting wire resistance. Make sure you do not touch the probe ends as your body will record a reading. If you are using a digital meter, connect the probe ends together and note the resistance of the included probe leads so that this can be deducted and allowed for within the tested circuit.

If possible make secure connections to the sockets by wedging in the meter probe tips so that you can wriggle the wiring to the coils about while a reading is registered in order to detect an intermittent situation, i.e. connection, wire or coil winding.

Next, using the highest ohms reeding, test all pin outs for a possible short circuit to ground, again while moving things about.

Report the results and we can move on with the diagnosis. You have a curly one which will test your patience, and mine. LOL

PS It would have been best to carry out these tests with a hot engine but I gather yours is NBG.
Thanks for your suggestions - I have some data and some questions. My connector going from the igniter to the coils has only 7 pins, not 8. Six of the pins go to the coils, and one is "ground" which appears to be generated from the case of the igniter as it is bolted to the firewall. So I'm not quite sure what your pin #s indicate, or what you mean by "that is between the wiring going to the coils." I have a digital multimeter that automatically reads in ohms, kilo-ohms (Kohm), or mega-ohms (Mohm) depending on what resistance it finds - the resistance reading with the probe leads touched together is very small - about 0.8 ohms. I tried connecting each of the 6 coil pin-outs to the ground pin, and they are all about 0.67 Mohm. I also tried measuring each of the 6 coil pin-outs to actual ground (the negative battery terminal, with a fully charged battery hooked up), and they were also all around 0.67 Mohm. This seems odd to me, since it implies that the coils are already somehow "grounded" (maybe just by being connected to the spark plugs that are in the grounded engine block) without the "ground" pin being connected to a "case-grounded" igniter. I'm not sure whether these numbers are helpful, since I'm not sure what the pin designations are on the diagram you're referring to.

Anyway, I also tried measuring the resistance between each coil pin-out and each of the other coil pin-outs to see is somehow one or more of those wires were rubbing together, and got a very high value, about 12.3 Mohm, for all the combinations.

Also, I tried all of the above while shaking/wiggling the wires around, but never got a hint of an intermittent open or short circuit.

To answer other concerns: this seems to be the only electrical problem the car has - everything else works, from the radio to the head and tail lights, windows, wipers, etc.

I have not checked for an over-charging alternator, as the car currently will not start, but will do so immediately after getting it started, assuming that will eventually happen!
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Old 10-01-2018, 04:44 AM
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Re: '92 SVX burning out ignition modules?

Quote:
Originally Posted by jlaguardia View Post
Thanks for your suggestions - I have some data and some questions. My connector going from the igniter to the coils has only 7 pins, not 8. Six of the pins go to the coils, and one is "ground" which appears to be generated from the case of the igniter as it is bolted to the firewall. So I'm not quite sure what your pin #s indicate, or what you mean by "that is between the wiring going to the coils." I have a digital multimeter that automatically reads in ohms, kilo-ohms (Kohm), or mega-ohms (Mohm) depending on what resistance it finds - the resistance reading with the probe leads touched together is very small - about 0.8 ohms. I tried connecting each of the 6 coil pin-outs to the ground pin, and they are all about 0.67 Mohm. I also tried measuring each of the 6 coil pin-outs to actual ground (the negative battery terminal, with a fully charged battery hooked up), and they were also all around 0.67 Mohm. This seems odd to me, since it implies that the coils are already somehow "grounded" (maybe just by being connected to the spark plugs that are in the grounded engine block) without the "ground" pin being connected to a "case-grounded" igniter. I'm not sure whether these numbers are helpful, since I'm not sure what the pin designations are on the diagram you're referring to.

Anyway, I also tried measuring the resistance between each coil pin-out and each of the other coil pin-outs to see is somehow one or more of those wires were rubbing together, and got a very high value, about 12.3 Mohm, for all the combinations.

Also, I tried all of the above while shaking/wiggling the wires around, but never got a hint of an intermittent open or short circuit.

To answer other concerns: this seems to be the only electrical problem the car has - everything else works, from the radio to the head and tail lights, windows, wipers, etc.

I have not checked for an over-charging alternator, as the car currently will not start, but will do so immediately after getting it started, assuming that will eventually happen!
Apologies, my bad and typo. Yes 7 pins and not 8.

I gather than you have taken measurements at the plug which attaches to the igniter with the plug removed and are have measured 0.67 ohms between each pin which goes to a coil and ground, i.e. you have therefore correctly measured each of the coil primary windings together with its connecting wire. If so that is fine.

I presume that you have taken into account the meter lead resistance and your meter has read 1.47 ohms. Please confirm.

Please also confirm that where you have shown 0.67 "Mohm" you have meant ohms and not meg ohms. Your typo? LOL

This would show that at 0.67 ohms your coils have a resistance at the low end of the specified figures and will be drawing the maximum allowable current and placing the maximum allowable load on the igniter. However you have six new coils which all read very close to the same figure so that it must be reasonable to assume that none are faulty.

One end of both windings within the coil are connected to ground. Therefore you will measure the same primary coil resistance between its pin out and any reliable ground point. The primary windings is energised between LT and ground and the secondary discharges HT to ground.

Your measurement showing 12.3 meg ohms between conductors indicates that there are no short circuits involved in the LT supply triggering the coils.

As I understand, it you fitted a new igniter and new coils simultaneously. As a long shot, could the new coils be from defective batch with coils of excessively low resistance, (wrong choice of winding wire, coil winder with a faulty counter, who knows) thus overloading the igniter outputs? Check new coils against used coils and compare. In the circumstances every possibility must be covered. Furthermore if you find a faulty used coil let us know as this will provide a worthwhile overlying clue concerning the original igniter failure.

Although you can't check for a possible nasty voltage from the alternator, with the ignition on you can verify that the igniter is getting full battery voltage. This is important to confirm.
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Old 10-01-2018, 03:17 PM
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Re: '92 SVX burning out ignition modules?

.
Since composing the previous post, I have again carefully studied the wiring diagrams and find that the igniter and coils are switched by the igniter in the negative, rather than the positive, supply leg.

This means that you should ignore my advice:-

"Although you can't check for a possible nasty voltage from the alternator, with the ignition on, you can verify that the igniter is getting full battery voltage."


The igniter receives positive voltage, via the six trigger circuits from the ECU, and switches the negative ground circuit to the coils. This rules out any problem relating to the alternator.

The coils all receive positive voltage, via a connection at the second 8 pin plug connector within the loom, which runs from the igniter to the coils as I mentioned earlier but appears not to have been found. With the ignition energized you must find and check for voltage at this connector on the plug side at pins 5 can 6, and the black/white wires which become a common connection on or after entering the loom.

It turns out that I did not make a typo and you will have to accept that it is difficult to verbally communicate regarding this sort of complex problem and patience is required, but we will get there. LOL

At this point I am not convinced that the problem is confined to the igniter. When changing igniters your could have corrected some obscure faulty intermittent connection which again failed later. Give this some thought.
.
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Old 10-02-2018, 11:58 PM
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Re: '92 SVX burning out ignition modules?

Quote:
Originally Posted by Trevor View Post
Apologies, my bad and typo. Yes 7 pins and not 8.

I gather than you have taken measurements at the plug which attaches to the igniter with the plug removed and are have measured 0.67 ohms between each pin which goes to a coil and ground, i.e. you have therefore correctly measured each of the coil primary windings together with its connecting wire. If so that is fine.

I presume that you have taken into account the meter lead resistance and your meter has read 1.47 ohms. Please confirm.

Please also confirm that where you have shown 0.67 "Mohm" you have meant ohms and not meg ohms. Your typo? LOL

This would show that at 0.67 ohms your coils have a resistance at the low end of the specified figures and will be drawing the maximum allowable current and placing the maximum allowable load on the igniter. However you have six new coils which all read very close to the same figure so that it must be reasonable to assume that none are faulty.

One end of both windings within the coil are connected to ground. Therefore you will measure the same primary coil resistance between its pin out and any reliable ground point. The primary windings is energised between LT and ground and the secondary discharges HT to ground.

Your measurement showing 12.3 meg ohms between conductors indicates that there are no short circuits involved in the LT supply triggering the coils.

As I understand, it you fitted a new igniter and new coils simultaneously. As a long shot, could the new coils be from defective batch with coils of excessively low resistance, (wrong choice of winding wire, coil winder with a faulty counter, who knows) thus overloading the igniter outputs? Check new coils against used coils and compare. In the circumstances every possibility must be covered. Furthermore if you find a faulty used coil let us know as this will provide a worthwhile overlying clue concerning the original igniter failure.

Although you can't check for a possible nasty voltage from the alternator, with the ignition on you can verify that the igniter is getting full battery voltage. This is important to confirm.
Well, I'll try to answer the above questions here and the ones in your next post there.

Yes, I'm measuring from the 7-pin connector from the igniter to the coils, with the connector unplugged. Your description of an 8-pin connector still confuses me - you wanted "...the resistance between sockets 4,1,7 and socket 3. Also between 5,2,8 and 6." I cannot find an 8-pin connector; perhaps there is a different connector on different years of this vehicle? I kind of assumed that whatever diagram you're looking at showed pins 3 and 6 as grounds, and the rest of the pins going out to coils. Is that not correct? Anyway, my measurements, from the ground pin to any one of the pins to the coils, as near as I can tell, are consistently exactly as I typed them: about 0.67 MEGA-OHMS, a huge number, such that I did not bother to subtract the measly 0.8 ohms of "internal resistance" within the multimeter. I read a little about standard coils and see where you're getting the suggestion that "the readings should fall between 0.7 and 0.85 ohms, taking into account the connecting wire resistance." However, my readings are consistently in MEGA-OHMS. When I hold the multimeter probes out in space, it gives me an "infinite resistance"-type reading. When I touch the probes together, it gives me a very low reading (again, 0.8 ohms), but when I check the ground pin to any one of the pins to the coils, the reading jumps back into the MEGA-OHMS range, and the digits themselves are about 0.67.

I am out of town away from the vehicle at this time, so can't do the test on the old coils for a couple of days. I'll also unplug one of the new coils and do the resistance check with it disconnected.

See response to your next post.
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Old 10-03-2018, 12:39 AM
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Re: '92 SVX burning out ignition modules?

Quote:
Originally Posted by jlaguardia View Post
Thanks for your suggestions - I have some data and some questions. My connector going from the igniter to the coils has only 7 pins, not 8. Six of the pins go to the coils, and one is "ground" which appears to be generated from the case of the igniter as it is bolted to the firewall. So I'm not quite sure what your pin #s indicate, or what you mean by "that is between the wiring going to the coils." I have a digital multimeter that automatically reads in ohms, kilo-ohms (Kohm), or mega-ohms (Mohm) depending on what resistance it finds - the resistance reading with the probe leads touched together is very small - about 0.8 ohms. I tried connecting each of the 6 coil pin-outs to the ground pin, and they are all about 0.67 Mohm. I also tried measuring each of the 6 coil pin-outs to actual ground (the negative battery terminal, with a fully charged battery hooked up), and they were also all around 0.67 Mohm. This seems odd to me, since it implies that the coils are already somehow "grounded" (maybe just by being connected to the spark plugs that are in the grounded engine block) without the "ground" pin being connected to a "case-grounded" igniter. I'm not sure whether these numbers are helpful, since I'm not sure what the pin designations are on the diagram you're referring to.

Anyway, I also tried measuring the resistance between each coil pin-out and each of the other coil pin-outs to see is somehow one or more of those wires were rubbing together, and got a very high value, about 12.3 Mohm, for all the combinations.

Also, I tried all of the above while shaking/wiggling the wires around, but never got a hint of an intermittent open or short circuit.

To answer other concerns: this seems to be the only electrical problem the car has - everything else works, from the radio to the head and tail lights, windows, wipers, etc.

I have not checked for an over-charging alternator, as the car currently will not start, but will do so immediately after getting it started, assuming that will eventually happen!
The fact that you are measuring 0.67 meg ohms indicate that either (1) the wires or connections making the circuit to to the coils is virtually open i.e. not properly connected or (2) all coil primary windings open circuit i.e. burnt out.

Obviously one must presume (1) indicates the trouble condition.

According to the US electrical manual I have, courtesy of svxcess many moons ago, the loom running from the igniter to the coils has an eight pin plug/socket connector within its length but you have been unable to find it.

Surely it must exist it is the point where the coils are supplied with their positive battery supply via fuse 16, which becomes energised when the ignition switch is turned on.

I no longer the a car so am unable to look for this obscure connector which we must now assume it is the gremlin we are seeking

Please. please is there a member following this thread who can help us out here in locating the elusive connector?
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