GM Service Manual Online
For 1990-2009 cars only

Data Link Connector (DLC)

The DLC is a standardized 16 way connector located below the instrument panel and close to the steering column. Both the connector design and location are dictated by industry wide agreements.

All DLCs are required to provide a power supply, hot at all times, to Pin 16. This circuit is used to power the scan tool. All DLCs supply a power ground at Pin 4 and a clean signal ground at Pin 5.

The Class  2 serial data circuit is provided at Pin 2 of the DLC.

The Class 2 Serial Data Line CKT 1807 (PPL) is wired to the DLC at terminal 2.

Class 2 Serial Data Link

The data link is configured as a ring with discrete lines entering and leaving each module. This allows communications to the modules on the ring if one of the two discrete circuits is open.

The control modules on the Class 2 Serial Data Line can include the flowing:

    • Cellular Telephone Module
    • Continuously Variable Road Sensing Suspension (CVRSS) Module
    • Dash Integration Module (DIM)
    • Driver Door Module (DDM)
    • Electronic Brake Control Module (EBCM)
    • Inflatable Restraint Sensing and Diagnostic Module (SDM)
    • Instrument Cluster (IPC)
    • Instrument Panel Integration Module (IPM)
    • Memory Seat Module (MSM)
    • Navigation Data Processor
    • Powertrain Control Module (PCM)
    • Radio
    • Radio Amplifier
    • Remote Keyless Entry (RKE) Module
    • Rear Integration Module (RIM)
    • Steering Column Module
    • Theft Deterrent Module

Simple Bus Interface (SBI) Serial Data Line

SBI does not communicate with the scan tool via the DLC. SBI information is interpreted by the driver door module (DDM) and transmitted on the Class 2 data link by the DDM.

The simple bus interface (SBI) is used for serial data communication between the four door modules as well as the driver door switch (DDS).

Refer to Diagnostic System Check - Power Door Systems