GM Service Manual Online
For 1990-2009 cars only

Class 2 Communications

The Class 2 serial data link allows specified modules (some are optional) to transmit, receive, or exchange data;

    • Powertrain Control Module (PCM)
    • Automatic Transfer Case (ATCSC)
    • Electronic Brake Control Module (EBCM)
    • Inflatable Restraint Sending and Diagnostic Module (SDM)
    • Body Control Module (BCM)
    • Electronic Climate Control Module (ECCM)
    • Power/Memory Seats
    • Instrument Panel Cluster (IPC)

The Class 2 serial data link allows a Scan Tool to communicate with these modules (listed above) for testing purposes, checking for Diagnostic Trouble Codes (DTCs), and to activate/enable/disable functions. These communication circuits are bussed together via a splice pack (SP201) which ensures a connection between the Class 2 communication circuits.

The Data Link connector has a ground for the serial data signal exiting the Scan Tool.

The Scan Tool is also supplied power and ground at the Data Link connector.