GM Service Manual Online
For 1990-2009 cars only

The data link connector (DLC) contains the following components:

    â€¢ The UART serial data line (CKT 800)
       - The UART serial data line (CKT 800) allows the following components to communicate data with each other:
   â€¢ The Powertrain Control Module (PCM)
   â€¢ The inflatable restraint diagnostic energy reserve module with sensor(SDM)
   â€¢ The Electronic Brake Control Module (EBCM)
       - The UART serial data line allows a scan tool to communicate with these modules for diagnosis and testing.
    â€¢ The class 2 serial data line (CKT 1807)
        The class 2 serial data line allows a scan tool to communicate with the PCM for diagnosis and testing.
    â€¢ Unswitched voltage (B+) (CKT 540)
    â€¢ Ground (CKT 650)