GM Service Manual Online
For 1990-2009 cars only

Class 2 Serial Data Link

The Class  2 serial data link allows these modules to communicate data with each other:

    â€¢ Body Control Module (BCM)
    â€¢ Driver Information Display Module
    â€¢ Driver Seat Adjuster Memory Module
    â€¢ Electronic Brake Control Module (EBCM)
    â€¢ Inflatable Restraint Sensing and Diagnostic Module (SDM)
    â€¢ Instrument Cluster
    â€¢ Powertrain Control Module (PCM) / Vehicle Control Module (VCM)
    â€¢ Transfer Case Shift Control Module
    â€¢ Vehicle Interface Unit (VIU)

In addition, the Class 2 serial data link allows a scan tool to communicate with these modules for diagnostic and testing purposes. The Class 2 serial data link is located at the DLC connector.