I have been presented with an interesting project. Without going into too much detail (because there isn't much detail yet), did GM do any funky things with high speed CAN across different platforms?
I am thinking here about using a PCM from one car and an electronic instrument cluster from another, and the question is if there is a single generic comms protocol or if there's going to be weird compatibility issues.
Anything I have found on a quick search involves making aftermarket gauges work, which the opposite of desired. This tells me that either nobody has done this yet, or it is so plug and play that it's not worth making note of.
I guess i always ask the really esoteric questions 
I'll try to think of a different angle to approach the question and hit up the usual sources again...
Sorry, I didn't see this earlier.
A lot of the messages are pretty standard across different GM platforms, but they evolved over time. If your parts are from a similar era, it should be fairly simple to get them to talk. The GM symbol maps are out there, even if they're not explicitly published anymore.
In reply to Keith Tanner :
Thanks!
The project is in the "general idea" phase. We'd like to do something like use a Corvette instrument cluster/HUD setup but might not necessarily want to use a Corvette OS in the engine controller, since the vehicle will by necessity be drive by cable. (Although I may have an idea for a workaround for that...)
I shan't get into the chicanery with the potential transmission/controller. If the word is go, and it works as envisioned, it'll be pretty slick.
Let me know if you get there, I might have some documents that would help.
Depending on the year of what you are looking to do, adding drive-by-cable to a Corvette PCM is as simple as doing a segment swap in EFI Live to add the drive-by-cable and remove the drive-by-wire. You can also add or remove transmissions to the Corvette PCM, allowing for a 4L80 trans or a manual trans on an original 4L60 trans or vicey versey.
That applies to the old LS series stuff, late 90s to mid 00s. Not sure how it applies to the later stuff or if you are using HP Tuners instead of EFI Live.
In reply to 93gsxturbo :
There are few PCMs that can do drive by cable. Most do not have the driver circuitry for the IAC motor. The only PCMs that I have seen that can go both ways were in trucks that were either/or during the same year range.
4 speed transmissions are right out.
What is the model and year range you are trying to work with?
http://lt1swap.com/cable_conversion.htm
93gsxturbo said:
What is the model and year range you are trying to work with?
It's all very up in the air at this point, depending on what will work with what. (Don't you just LOVE the "floating contingencies" part of a project?) Knowing what WON'T talk to what will help nail down this sort of thing.
I do know that it was an interesting trip my boss's dad had when he LS3-swapped his Solstice. Apparently it required a daisy-chain of compatibility like that episode of I Love Lucy where they had to translate English to some other language through two or three intermediaries. (Apparently it was something like a CTS-V PCM with a somewhat custom OS, and a Cobalt BCM with some tweaks, if you want a V8 Solstice where everything works, including the cruise control)
That car got me familiar with EFI Live, a piece of software I am happy to say I never had to actually WORK with. What garbage. HPTuners is far more intuitive and usable.
And today I found out that one of Da Boss's kids wants a Miata, which will eventually get a V8 swap, and the leaning is towards an NC. I introduced him to Flyin' Miata on my lunch break.
