Cross posted to V6 board.
1991 Camaro RS 3.1
I'm struggling with my ignition
Here's what I have, New coil, New Dizzy.
Main power into the coil is 12 volts tach wire is also reading 12 volts. (Grey Connector)
Black connector also has 12 volts coming from both sides of the coil. I've read there should only be 12 volts to one terminal but I have 12 out of the coil itself on both sides.
Ground wire (G terminal) on the ICM is grounded.
Both the coil and the pickup coil read good testing Ohms, but I have no spark. I'm super confused here.

 

A few things come to mind here.............

First off, yes having +12V on the fat pink wire to the coil with the key on is a good thing. Does that +12V remain present when the key is turned to engage the starter?

Yes, you will read +12V on both sides of the primary coil because the coil's primary winding is of such a low resistance. One side of the primary coil is of course +12V, while the side of the primary coil connected to the ICM will be switched to ground six times for each full rotation of the distributor. The ICM will only switch the negative going side "on" when it senses distributor rotation, so with it stationary, both sides of the primary coil will show +12V, since the ground side is "open" . If the ICM were to keep the primary coil energized with no distributor rotation, the coil or ICM could be damaged if the key was left on without the engine running for any prolonged length of time. Remember, this is a "duty cycle" type of circuit where current is never supposed to flow 100% of the time. I hope this makes sense to you? A great check would be to use an old fashioned analog voltmeter (like my trusty Simpson 260, for example) connected between the primary coil's negative side and actual ground, and see if the meter's needle bounces while cranking the starter. This would provide one diagnostic clue to help track down if your spark loss is related to the coil's primary or secondary windings.

Other points to ponder;

While you say the parts are all new, something being brand new is not, in itself, 100% proof that those parts (ICM and coil especially) are in fact perfectly operable ! You have NO idea how many brand new parts I've seen come out of their brand new boxes being totally junk, due to everything from manufacturing defects to someone having dropped it somewhere along the supply chain, and destroyed it by blunt force.

And now, I gotta ask, have you checked that the distributor does in fact turn when you crank the starter? A broken timing chain is one thing that could cause the distributor to not turn and thus produce no sparks if everything else is in fact good.

And lastly, your car has a "Distributor" , , , , , a "Dizzy" is a loose woman in a dive Bar that ya hope to bang on a Saturday night, and, even if you proudly proclaim "Cross posted to V6 board", , it's still against TGO rules to do so

 

Appreciate the info, Yes the distributor is turning. No I don't want to bang any lose chicks at the bar . I've experienced many bad parts from the box as well, I'll get someone to crank it for me next time I have the chance so I can check to see if it's switching. if not would that likely be an ICM issue?

 

I laughed hysterically after reading this!


My "Body Count" is disgustingly high...
And I have heard plenty of "Loose Female" terminology, but never heard "Dizzy" before...

I am adding that one to the Daily-Vocab. for the Ladies that are walking kinda' funny after visiting me!

 

Picture the way Marilyn Monroe used to walk, , , , Dizzy.....

(Yes I realize Norma Jeane was supposedly quite intelligent, it's the "Marilyn" persona to which I refer)