Perplexing No Spark

[hoogiesngrinderz]

Need to borrow a GM small cap HEI just to rule out the distributor as a whole?

[Blue_Thunder]

Okay to recap my car never had VATS, I am using a PROM from and 89 thats slightly changed (and VATS was disabled in the PROM, verified by the TGO member I bought it from).

My camaro had a large cap and coil dizzy. I converted using EFI Connections wiring harness adapters to a small cap external coil setup.
Distributor is brand new, Petronix Flamethrower.
Ignition coil is not firing its secondary wiring for its 50,000 volts spark.
Ignition coil tested good and even swapped it out with a spare I had.
I have 12 volts to the Ignition coil key on.
I have 12 volts to the ICM with key on.
ICM was tested at a local parts store and it past the test (5 times).
Installed a new pickup coil.
Bench tested new pickup coil. Put out .735 AC voltage
Installed a new ECM.
All grounds on back of harness connected to the rear cylinder heads.

[Blue_Thunder]

Update, just got back from my vacation. Was hoping time away would maybe let me see something new. I got a new test light and back probbed the ppl/white ground pulse reference on the harness side of the connecter, and immediately the test light lit up. And while cranking it pulsed. The blk/red wire is also grounding. At this point I have nothing left I can think of to test.

[NullHead]

So technically, as long as you have B+ to one side of the coil that turns on/off with the ignition switch, you've verified your ICM is working by finding a pulsing signal at the black wire at the coil, that really only leaves secondary ignition components as being the issue. Silly question, is your engine ground connected? Because it sounds like assuming your ignition coil is okay, you should be getting spark out of the secondary side of the coil.

[Blue_Thunder]

So technically, as long as you have B+ to one side of the coil that turns on/off with the ignition switch, you've verified your ICM is working by finding a pulsing signal at the black wire at the coil, that really only leaves secondary ignition components as being the issue. Silly question, is your engine ground connected? Because it sounds like assuming your ignition coil is okay, you should be getting spark out of the secondary side of the coil.

Engine ground is connected from the back of the passenger cylinder head to the firewall.

As a last ditch effort I tried a new distributor with the same results. No spark. I rechecked everything, still 12 volts at pink wire coming to ignition coil. Still 12 volts at pink/blk stripe wire at ICM (key on). Volt meter hooked up to secondary coil output (where dizzy coil wire plugs into) and have battery voltage while cranking. The ppl/wht wire going to the ecm pulse reference ground does pulse with my test light.

I have nothing else to try at this point.

[NullHead]

What if you pull the plenum off and install all your old stuff? Just to check for spark, obviously. You're sure this isn't just a bad coil?

[Blue_Thunder]

Found the issue last Friday night. I fixed my DVOM meter and ohmed out the signal wire from the ICM back to the coil. Ohmed high, so the wire while connected was broken enough that the signal wasn't getting through. Fixed the wiring and it fired right up. Now to fix the high idle...

[DynoDave]

Nice work young man!

[ruckusz28]

Good work, young detective