You are right, it is an GM spec and has to do with local area networks in GM-cars. Several controllers in the car communicate with this LAN and I assume it describes how they communicate.
My customer is helpless too.
I would apreciated if you send me that document also. I was looking for GMLAN specs to develope some communication software. I've been interested in GMLAN as a high communication protocol.
I changed the company in between. Since the spec was filed on the old company server I had no access but now a colleague from a related company sent me the file again. Many thanks to K. Fischer!
If anyone is interested please send me your email-address and you will recieve the spec soon.
I would apreciated if you send me that document also. I would like to develope a GMLAN interface for my malibu car and I need the GMLAN specs.
I hope you can help me.