GM Coil and Module Help Required

-
Wayne Miller

Wayne Miller

1962 Dodge Lancer Wagon
Joined
Apr 10, 2018
Messages
90
Reaction score
49
Location
Barrie Ontario Canada
IMG_1439.JPG


IMG_1440.JPG
The Pink wire on the right side lower terminal of the coil goes to Ignition Run terminal on the ignition switch upper terminal .
The Blue wire on the Right side upper terminal of the coil goes to the start terminal on the ignition switch.
The white and pink are jumpers from the Module to the coil.
The 2 Grey wires from the Module to the Distributor.
The motor turns over when ignition key is turned to start but I am not getting any spark.
The Distributor is a Mopar electronic.
Any suggestions would be appreciated.
 
Did that setup run at some point or is it a new install? Looks like it's been on there some time and ran at some point. I'd check fuses if there are any, if it's getting 12v swap out the module... they are dirt cheap and never bad to have a spare in the glove box.
 
Those GM modules are bad for going out and when they are gone, they are dead. Most of the ones I have had around I ended up giving away to friends stranded.

Check the module or get a new one.
They are making a GM hei that slips right in a SBM now. Just have to have room at the firewall.
 
Make ABSOLUTELY certain of your coil wiring RE: the two terminals together. I ran into "some coil" where the two siamesed terminals were NOT electrically the same.

This is the go-to diagram
4pin-jpg-jpg.jpg

[img]

1..Make absolutely certain the module mounting holes are grounded (electrically) and that the "tit" has been cut off so it sits flat on a heat sink
2...Pay attention to the pickup polarity as they affect timing what is called "rotor phasing
3....CHECK with a light or meter at coil + WHEN CRANKING as well as with key in "run" position to see if you have battery both times.

You MUST pick up the (usually brown) IGN2 bypass circuit wire or you will not have voltage when starting. The "run" IGN1 line goes DEAD in "start."

EDIT: Finally found it. THIS is what I'm talking about on the coil wiring

HEI8_coil.gif
 
Last edited:
It looks like you have the coil [-] wire passing over the pick up wires [ terminals G & W ].
There is a 2-300 v pulse on the coil [-] when the ign fires & can induce voltage into the p/up wires & cause false or no triggering. The high tension lead also looks close to the p/up wires.

Keep the coil wire & & HT leads away from p/up wires. It is a good idea to use co-axial microphone cable for the p/u wires & ground the outer braiding.
 
yeah check your coil, 4 connectors, identify the two pairs, one pair is + and one is -

coil + has 12 volt switched to it
run wire from the other of the pair to B on module
negative on coil to tacho and to diode and to C on module
W and G go to pickup and you will need to work out which way


you might have to look up orginal application of coil to find which pair is which.


or you have the pickup wires backwards, depends on the car the module was made for.
with them back to front you get, running rough with the igntion timeing wildly adjusted away from where it previously ran fine. Or not running at all.


see my post here, bit of a rant, but it has the part number for a diode you can use to protect your module and some links to help you decide that you have indeed made a good choice for your igntion set-up, and a link to show diode use on a jaguar GM module set up .
The module takes a "belt" of back EMF from the coil and the alternator if you stall the car when the alternator is FULL ON. think reversing up a steep drive on a cold morning
revs up in the 1500+, battery is flat-ish, alternator full on, you drive and you stall ,
altenator abruptly loses field power and spikes the eletcric system, taking out your module or damaging it so that it fails later at a very inoportune moment. that spike was fine on a car with little or no micro processors. you now have a simple one so some protection makes sense.
If jaguar peristed with this diode set up when using delco modules even when GM stopped i think its a good idea

post here
New release Distributor for Slant 6


Dave
 
Last edited:
Despite what post #6 says, your problem is probably listed in post #5. Reversed p/up leads does NOT result in no spark. The signal [ for spark ] is generated as the reluctor passes the trailing edge of the pole piece. When the p/up wires are reversed, it fires on the leading edge. The difference is usually about 30 crank degrees. However, the rotor-to-segment relationship has changed such that you can get crossfire in the cap. Result can be backfiring, engine kicking back, but it still produces a spark.
 
Yeah i didn't say it didn't spark, just that it wouldn't run, and i wasn't critesciing what you said, its totally relevant, so i didn't repeat it

Not sparking is also potentially a busted module and what you decsribe can also contribute to it being broken....

putting in a new one and breaking it again, is no good...

If a new one is purchased avoiding the problem that MIGHT have broken the last is financially sensible.

and you do get the odd one that is just faulty out of the box...

As bewy asserted check what he says and if it still a problem then the rest of us might have made a point that could help...

One other thing...the coil where it is, it is potentially beaming a magentic field right into the module

When the GM setup was first invented, with the coil in the cap directly above the rotor and the module they had difficulties. They discovered that, in that close proximity situation the coil orientation and the version of the module had to be set and choosen specifically to avoid interferance.

Using the coil connected the wrong way round or using a module for the pontiac version in a chevy set up resulted in problems. those problems were ironed out, but that doesn't mean you can't re create them by accident

i.e coil module and leads can interfere, however my set up is just a module hung off the side of the dizzy and the coil on the original mount with the wires trailing across and i have had no issues in 20 years. So trying it with the module and heat sink away from the coil might also work

Dave
 
I think you are incorrect about a couple things here. The alternator field does not cause a spike as long as the alternator is (normally) connected to the battery. The VR pulses the field to regulate. The coil field affects the module? No. There are hundreds of thousands of GM in cap HEIs in service through the years, some of them still RUN. I just ran into one the other day, an older pickup, and it had the original coil and module. Only thing ever changed was the cap and rotor.

Actually, effects, damage from EMI can more easily occur with an external coil / EFI, because the trigger wiring is longer, and if improperly routed, can be subject to interference from the secondary wiring, especially if solid core is used.

This was famous with MSD, known for "retriggering itself" due to the spark current causing a trigger--in the trigger wiring
 
Dave,
A lot of the problems you mention in post #8 never eventuated. I have the original GM info they released on HEI operation. Yes, different ign coils for Chev, Pontiac [ & different p/up coils ].
However, replacement HEI coils such as the MSD #8225 fit all in cap HEIs. Different p /up coils, yes because of CW & CCW rotation.
I did read that GM had concerns about the magnetic field from the starter interfering with HEI operation during cranking but I believe these proved to be unfounded.
For any body who thinks points are great & are all you need, the document states that HEI has 40% more voltage output & 85% higher energy level than conventional breaker points to "fire lean fuel mixtures even under the most adverse conditions".
 
67Dart273 said:
I think you are incorrect about a couple things here
Click to expand...
Quite possibly.... :) i do tend to just shout out what i think...

but there is something in it as far as i can tell, but my view or what it is is potentially wrong... Alternator is connected to battery +. which is connected to the diode setup which is connected to the 3 phase coils in the case. The action of a quickly changeing magentic field made by the rotor produces the voltage in the case windings to charge the battery and run the car...
Car Running and the field is at maxiumum, and the alternator is chargeing at 14.? volts, you might have 30 amps flowing in the case windings or at least out of the stud to the car/battery

stall it. the field is still ON, the field coil in the rotor is seeing 5 volts from the regulator becasue the battery just started the car and is flat-ish, and the ignition switch is in RUN.
But the rotation driving the production of 3 phase in the case windings HALTS abruptly. Big immediate change in interaction of field around rotor with the wireing in the coils in the case, you end up going from constantly varying AC generation north south north south across each winding as each segement of the rotor passes, to a stock-still North Souh across the coils that doesn't move, becasue the engine went from 1500 rpm to 0 in 1/4 of a turn.
field/rotor current increses (its now stopped, no impedence to flow) and case widing current drops like a stone.

What was a continually and fast variation in magnetic field, is now stock still. A big change in field. That 30 amps in the case windings just stopped abruptly as well. 30 amp to zero in a split second, also creates a magnetic pulse of considerable magnitude and how it combines with the one caused by just stopping the rotor i dunno.

what comes out or goes into to the battery + to or from the car, in that fraction of a second when you stall is open to debate. battery + is however connected directly via the igntion switch and then to the coil and module + and the other end of everything is earthed.
so what did the coil see and what did the module see when the voltage at battery + did something wierd. potentially big-er volts in a positive or negative way...... even if just 20 or 30 its out of the general tollernace for car electronics.

Yes its a half baked idea, its not well formed BUT it comes from:--

I had a situation a few years back, a massive gradient on the drive, if the fuel in the tank was low i couldn't start the car, nose down, tail up. I couldn't then open the garage door to get to the fuel can.... i could drive in but getting it back out again the next day was a problem, you needed a decent fuel level to park nose down on the drive, you could park in the garage below no problem with an empty ish tank. car lived in a garage under the house, no starting choke and ostensibly 6 carburetors 3x dcoe that don't work well when not warmed up. and its a manual

steepness gearing and fuel issues

in a hurry, without 5 minutes warm up, it was easy to stall it halfway up the drive, the kinda stall that is like a punch to the head, that you just can't manage to cause with a fluid coupled auto.
At the time i had 2.92: ratio rear end, an obnoxiously heavy clutch and a less than easy reverse gear ratio.
I did 2 or 3 modules this way until i moved house...
and of course you never knew if it was fuel level or module. feel my pain.
So trip to get can of fuel, which on occaions resulted in no change, was followed by module replacement...and suddnely all is well again.
If this happend in random places i'd suspect low quility modules... its something else.... but it all happend in the exact same spot with the same scenario on days when you least needed it to happen.

and i didn't really form this theory until i got talking to some of my mates about it, who run in the UK superstock series... i.e more $$$ invested in their cars than i will ever manage.

General consensus was that the emergency ON-OF switches they had in the tail of their cars came in a number of types appropriate for the electrical complexity of the car. For a points car with no ecu type stuff its an ON OFF switch. battery and alternator feed OFF. it isn't a complex thing. 3 or 4 stud mounted fat wires and job done battery in boot fuel pumps in or under boot, so near by.

but if you want to do it right you have a multi pole multi throw switch for different circuits in the car, and the throw of each pole is offset slightly to avoid a situation similar to above, where the unexpected removal of power casues bad stuff to happen
more studs and connections.

igntion circuitry off first, then fuel system (an electric motor) next, then battery and alternator disconnect, from what i remember, i might have it the wrong way.
All in a 1/4 turn of the big red switch.
Seemingly do it the other way with the engine running at more than idle and you might take out your ECU and other electronics. (we are talking a track emergency, fire suited man swicthes off car because you can't, unconscious or thottle jamed, upside down etc and a few of them had been upside down etc in the past)
Then they all had a spirted conversation, some guys insited this was the case, alternator and coil could kill your expensive stuff....there were doubters who said it was all BS... you are all daft just keep it simple etc.

but the guys running expensive electronic equipment sided one way and the guys running basic stuff didn't seem to care, its hard to break a dual point distributor.

but maybe this is why their MSD6 boxes keep dieing.... ??

since those days, ive included a zener diode to clamp the reverse voltage the module can see i've not had a problem. but i also don't have the facilties like a stupid steep drive to promote a stall, under medium rpm and medium torque on a cold engine. Better gear ratio torsen diff better ignition coil different 4 speed and a better tune.

the issue could have been driven by the ON OFF ON at the key to restart the car...when preceeded by a stall....i dunno.

I'll admit one mans experience doesn't make for a thing...but in my world something is going on, and by coincidence i found a small group of guys who also think its a thing....

it might not be and they have more to damage than I do. A more expensive emergecy cut out might be cheap insurance, and that could be drving their view.

Bewy yes i have got my module and pickup wires mixed up. some pontiacs spin the other way....


Dave
 
Last edited:
Well all I can say is you need to get your self an oscilloscope and go to work. If you disconnect the BATTERY while the alternator is operating, it will make a spike, and the more it is charging, the spike could be huge. But if you just kill the field, no, the load on the output will simply load it and it will die out. This is a non issue.
 
Screenshot_20230615-031145_Gallery.jpg


Screenshot_20230615-031217_Gallery.jpg


Simple Straight 12 volt to the good E-Coil

Screenshot_20230615-031115_Gallery.jpg

Fitment 1995 F150 when ordering from Rock Auto, simple 2 post e-coil.

Screenshot_20230524-065453_Gallery.jpg



Screenshot_20210402-152341_Gallery.jpg


☆☆☆☆☆
 
Man, I did the "trailbeast" style conversion on every vehicle since he showed it.
My car always fires in the first revolution .
Car sits for years, fill the float bowl, pump twice, instant fire . It's absolutely unbelievable after years of crank-crank- crank .
Install it on every build since, coupla dozen anyway, never a failure .
Kinda miss that sound of the starter, wah-wah-wah.
Maybe I can record it, re-play triggered by the starter .
 
Dave,
All Pont V8s spin CCW. Late 70s Pontiacs had Chebbies, they turn CW.

Also agree with 67Dart, alt field is a non-issue. The battery acts as an almost short cct for the alt & absorbs any spikes. This would have all been researched when the systems were designed. Now, if we talk about Lucas Electrical, they were not known as the Prince of Darkness for nothing...
 
You must log in or register to reply here.
-

Back
Top