HELP!! Crank, No Start, Possible PCM issue?
Hello all, I'm a new member, but have followed the forum off and on for many years. My experience with LT1s is moderate, but not expert. I have had 3 F-bodies w/ LT1 and even swapped one into an S10 years ago.
I have recently obtained a 93 Z28 M6 that has been sitting for several years...one of those ran when parked kind of deals. Upon initial cranking of the engine, I have learned that ignition spark is MIA. Being somewhat seasoned with LT1s, I immediately blamed the Opti. I figured, What the heck, its several years old, its probably due for one whether it fixes the issue or not. I wasn't surprised to see the absence of spark after the new Opti. I found an OG service manual for the ignition system from a program we use in our shop at work. I started with the coil and ICM and worked my way back to the Opti. Checking the plug at the opti, then back to the one by the intake, the results are as followed. D=good ground, C=battery voltage, A&B neither have anything. The service manual says to check for 5V and I'm getting nothing. I checked cont. between the pigtail and PCM with little to no resistance. I also checked for the 5V directly at the PCM with poor results as well. I hate to point my fingers at the PCM, since its not 100% common for failure there, but that's what I'm lead to believe. I would like to hope I have overlooked something, beings the 93 PCM is like a dinosaur. I've called GM dealerships, and all PCMs are on national backorder. If in fact the PCM is toast, my only option is paying a premium for a used one someone has laying around. If anyone sees that I have overlooked something, please point me in the right direction. Thanks