I have not spark what so ever i have replaced opti twice with know working ones, coil with known working one and icm, I did apply the heat transfer grease for every module installed. I also took the bracket off and disassembled completely, then ground down on a bench grinder until bare metal was showing on nearly the while bracket, all grounding seems to be fine when i use a test light on it.

After replacing 2 icms i went to napa and got one the car fired up right away it died on its own but started right up again and ran for a while. I changed my plugs and now have no spark again. i have replaced icm 3 times since the car started for me still no spark....

I have done the tests for diagnosing a bad opti Terminal A and D read 12v C has a good ground and B measures approx 2.5v ac while cranking. I also have checked my injectors and they are spraying.

Also i have had 3 different computers in the car and no difference.

My only thoughts are that maybe i am frying the icm. How can i determine if this is happening.

 

That happened to me last year. It actually started a few years ago. Turned out to be the harness connector to the ICM which had an intermittent open. Now I have a couple good ICM's for spares. Maybe you will get lucky too. I found it by wiggling the harness at the ICM connector. You have any friends with a 4th gen LT1? Try a bad ICM on their car.

 

ZZ you are the man i have spark again. The connector was my problem must have been shorting out somewhere inside. thanks so much you saved me lots of hair and money hahaha

 

Tell me about it. It bugged me for a couple years. It would be fine for months, then started to stumble, then it was fine. Did all the checks, swapped the opti, etc. I found it by accident one day while swapping ICMs. Glad it was an easy fix for you too.