The CCM does contain an EEPROM where things like VIN, available options (C60 vs C68 climate control, engine type, etc) and odometer are stored. These values are volatile until 100 miles have accumulated on the odometer, after which a bit is cleared that causes the CCM to no longer accept download requests to RAM (EEPROM). Inside the CCM somewhere is a pin that, if grounded, will override this bit. I haven't taken a CCM apart so I have no clue where it would be, but I highly doubt it'll just be plainly marked so that anyone and their dog could find it since it's so critical to the integrity of the data on the CCM. Additionally, as far as I know no one has actually reverse-engineered the communication required to retrieve and/or set the values in this EEPROM. I do have a Tech 2 handy, but as neither of my Corvettes have less than 100 miles on them and I don't feel like tearing apart perfectly-working CCMs, I haven't bothered to see if my Tech 2 comes with those abilities.

The CCM does not have any ability to query other modules to set values in EEPROM. These are only set by an external tester (Tech 1A, Tech 2, etc).

The CCM is also what drives the digital dash on our Corvettes, and is the bus master, and the central security system for the vehicle, among many other tasks. It even handles control of the rear defroster array, independent of the climate control. Replacing the CCM with something else would be a massive undertaking.

Replacing the PCM with something that makes the CCM happy, however, is not. It was already done by Torqhead using a '411 PCM. As for the protocol, the data you're looking for is $40 and $41, where $40 is the CCM making a regular poll of the PCM, and $41 is the response from the PCM containing all available data. The structure of this is in the image below.

ecmccm.jpg

I agree that having open-source tools for all of these functions should be a priority. GM certainly isn't going to support us any longer, and having Torqhead be the only ones who can sell you a solution is not optimal for those of us who would want to cobble something together ourselves. I'm still planning on reverse engineering the ABS communication so that people can recalibrate their TPS or perform the auto bleed function on 95-96 Corvettes without ponying up the cash for a Tech 2 or praying their local Chevy dealer can help for exactly that reason.