Information Bus: Description and Operation

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 J 1962 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.

The microprocessor-controlled modules in the vehicle communicate with each other through the serial data lines. This vehicle uses 2 serial data lines:
^ The Entertainment and Comfort serial data line
^ The Class 2 serial data line

ENTERTAINMENT AND COMFORT SERIAL DATA LINE
The Entertainment and Comfort serial data line is UART-base communication system. UART serial data lines have a master of the serial data line and remote transceivers. The master controls the message traffic on the serial data line by polling all of the remotes (control modules). The master then waits for the proper response. The control modules on the Entertainment and Comfort serial data line can include the following modules:
^ Radio
^ Remote playback device - (CD) changer

The Entertainment and Comfort serial data line is not connected to the Data Link Connector (DLC), so it can not be accessed with a scan tool. The Entertainment and Comfort serial data line is diagnosed in the Entertainment section. Refer to Diagnostic System Check Radio/Audio System in Radio, Stereo, and compact Disc.

CLASS 2 DATA LINE
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:
^ Body Control Module (BCM)
^ Continuously variable road sensing suspension (CVRSS) module (W/F45)
^ Electronic Brake Control Module (EBCM)
^ HVAC control module
^ HVAC control processor
^ Inflatable Restraint Sensing and Diagnostic Module (SDM)
^ Instrument Panel cluster (IPC)
^ Memory Mirror Module (MMM) (W/A45)
^ Memory Seat Module (MSM) (W/A45)
^ Powertrain Control Module (PCM)
^ Radio
^ Radio Interface Module (RIM) (W/UQ4)
^ Remote Control Door Lock Receiver (RCDLR)
^ Vehicle Interface Unit (VIU)

The VIU has only one communication line connection to the Class 2 serial data circuit.

"For the description of RPO Code(s) shown in this article or any of the images therein, refer to the RPO Code List found at the Vehicle/Application and ID." RPO Codes