Originally Posted by darrensls1

I think I found the codes that seemed to be engine/ignition related.

DTC 36 – Distributor Ignition System (Faulty High Resolution Pulse or Extra Low Resolution Pulse Detected)

DTC 42 – Ignition Control (IC) Circuit (Shorted or Grounded Circuit)

Sound like my opti is going bad?

Originally Posted by darrensls1

I sure hope it all works after this. I also hope this opti unit is plug and play. If it requires ignition timing with an oscillator or some crap then I'm screwed.

Originally Posted by MatthewMiller

Hey, this might be good news: the problem may be easier to locate than I was thinking. I was able to “print” the relevant pages out of my factory service manual for all your CCM codes (31-38). If you look at what each code is and then look at the diagram at the top of the page, you’ll see that it’s all related to the four digital circuits on the “F” connector of the CCM (LCD Data, M Clock, Data Clock, and Data Strobe). There are eight codes, two for each signal. If you read the description under the diagram, you’ll see that the two codes for each signal correspond to a bad reading when the CCM first powers up: one code means it saw a high signal when it should have been low, and the other code means it saw a low signal when it should have been high. That’s on one single connector, “F”, going into the CCM, which is what sends data to the LCD display (the same display where your codes were shown).The fact that all the codes are historic tells me it’s intermittent. Also, the fact that your check engine light kept coming on and turning off again makes me think that. So something may just be physically wrong with that connector, or maybe at the other end where those signals plug into the instrument cluster. Or maybe even something in between. Did they mess with anything in the dash at all? Did you try to remove/replace the radio? It’s possible the CCM itself is causing the problem. It’s also possible that the LCD cluster is causing the problem. The CCM is behind the radio in the dash. It’s a bit of a pain to get to, but it can probably be checked by removing the radio, and then someone can carefully check that connector and the wires to/from it. The manual goes in-depth into diagnosing and fixing the issue, but someone is going to need proper diagnostic equipment to do it.

I’d try clearing the codes first and seeing if the CCM codes come back. If they do and the display is actually working when you drive it, you may just be able to ignore it. The good news is that this is a pretty localized problem – all the codes come from one place. I don’t think anyone needs to chase grounds all over the chassis, which is what I was afraid of. Also, none of these CCM codes should result in stranding you. At worst I think the LCD cluster could stop working and the check engine light keeps resetting.

Originally Posted by MatthewMiller

Given the coolant leak, seems like a good chance the Opti actually was getting wet and the module was periodically fizzling. It's probably too late now, but a friend of mine (also with a 95) put two different Duralast (Autozone) optis on his LT1 and they were both DOA, confirmed. He finally sent his original to the Optidoc for a rebuild and it's been fine ever since. If you have the time to wait, it may be good to wait until you can get a better replacement than Duralast. I'd say the same for their shitty water pumps, but I don't have good US-made/rebuilt option to suggest to you.

Speaking of that friend, it was him who had the same series of CCM codes as you, not a thread on here (memory's fading fast with age...what were we talking about?). Here's what I emailed him: