GM Service Manual Online
For 1990-2009 cars only

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

    • The UART serial data line (CKT 800)
       - The UART serial data line (CKT 800) allows the following components to communicate data with each other:
   • The powertrain control module (PCM)
   • The inflatable restraint diagnostic energy reserve module with sensor
   • The electronic brake control module (EBCM)
       - The UART serial data line allows a scan tool to communicate with these modules for diagnosis and testing.
    • 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.
    • Unswitched voltage (B+) (CKT 640)
    • Ground (CKT 1550)
    • The theft deterrent module test light output (CKT 728) (SEO equipped vehicles only)
        The theft deterrent module test light output allows a test lamp or a scan tool to monitor the theft deterrent module.