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 agreement to follow SAE J1962 standards.
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.
Class 2 Serial Data Circuit
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.
A total list of the control modules on the Class 2 Serial Data
Circuit can include the following:
| • | Powertrain Control Module (PCM) |
| • | Electronic Brake Control Module (EBCM) |
| • | Remote Function Actuator (RFA) |
| • | Rear Integration Module (RIM) |
| • | Compact Disc Player (CDX) with U1S |
| • | Inflatable Restraint Sensing and Diagnostic Module (SDM) |
| • | Dash Integration Module (DIM) |
| • | Instrument Panel Integration Module (IPM) |
| • | Memory Seat Module (MSM) with A45 |
| • | Driver Information Center (DIC) |
| • | Instrument Cluster (IPC) |
| • | Pass-Key® III Vehicle Theft Deterrent Module (VTD) |
| • | Driver Door Module (DDM) |
| • | OnStar Vehicle Interface Unit (VIU) |
The following modules have only one communication line connection to
the Class 2 serial data circuit:
| • | Memory Seat Module (MSM) |
| • | Driver Door Module (DDM) |
| • | OnStar Vehicle Interface Unit (VIU) |
Door System Serial Data Circuit
The door system serial data circuit does not communicate with the scan
tool via the DLC. Door serial data information is interpreted by the driver
door module (DDM) and transmitted on the Class 2 data link by
the DDM.
The door system serial data circuit is used for serial data communication
between the four door modules as well as the driver door switch assembly
(DDSA).
Refer to
Diagnostic System Check - Door Systems
in Doors.
