Scan Tool Does Not Communicate with High Speed GMLAN Device: Notes
WARNING: This page is about a different car, the 2005 Saturn Ion Red Line, 2005 Saturn Ion 3, 2005 Saturn Ion 2, and 2005 Saturn Ion 1. However, it is still accessible from the selected car via links, so may be relevant.
Modules connected to the GMLAN serial data circuit monitor for serial data communications on the GMLAN network during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module detects a bus-off condition a DTC U2100 will be set. This DTC can be retrieved as history only.