Circuit Operation
DATA LINK CONNECTOR REPLACEMENTThe Data Link Connector is a 16-pin connector which allows the service technician to connect a scan tool to the vehicle. The DLC is located below the left-hand side of the instrument panel, near the steering column.
DATA LINK CONNECTOR OPERATION
The Data Link Connector (DLC) allows a scan tool to communicate with the Class 2 serial data line. The serial data line is the means by which the microprocessor-controlled modules in the vehicle communicate with each other. Once the scan tool is connected to the Class 2 serial data line through the DLC, the scan tool can be used to monitor each module for diagnostic purposes and to check for Diagnostic Trouble Codes (DTCs). Class 2 serial data is transmitted on a single wire at an average of 10.4 Kbps (10,400 bits per second). This value is an average; Class 2 uses a variable pulse width modulation to carry data and, depending on the message, it may operate faster or slower. The bus is active at 7.0 volts nominal and inactive at ground potential. When the ignition switch is in RUN, each module communicating on the Class 2 Serial Data Line sends a State of Health (SOH) message every 2 seconds to ensure that the module is operating properly. When a module stops communicating on the Class 2 serial data line, for example if the module loses power or ground, the SOH message it normally sends on the data line every 2 seconds disappears. Other modules on the Class 2 serial data line, which expect to receive that SOH message, detect its absence; those modules in turn set an internal DTC (Diagnostic Trouble Code) associated with the loss of SOH of the non-communicating module. The DTC is unique to the module which is not communicating. For example, when the Dash Integration Module (DIM) SOH message disappears, several modules set the DTC U1064. Note that a Loss of Serial Data DTCs does not normally represent a failure of the module that set it. A technician should use this technique to quickly identify which module is not functioning on the Class 2 Serial Data Line.
Data Link Connector Circuit Description
Battery positive voltage (B+) is provided from the ALDL fuse in the Rear Junction Block on CKT 3640 (ORN) to the Data Link Connector at terminal 16. The ground reference for the scan tool is supplied at the DLC terminal 5 on CKT 351 (BLK/WHT) and DLC terminal 4 on CKT 450 (BLK). The Class 2 Serial Data Line CKT 1807 (PPL) is wired to the DLC at terminal 2 and the CKT 800 (TAN) connects DLC terminal 2 to the Continuously Variable Road Sensing Suspension (CVRSS) module.
The control modules on the Class 2 Serial Data Line are as follows (some depend on vehicle option content):
^ Cellular Telephone Docking Station
^ Dash Integration Module (DIM)
^ Electronic Brake and Traction Control Module (EBTCM)
^ Instrument Panel Cluster (IPC)
^ Instrument Panel Integration Module (IPM)
^ LH Front Door Module (LFDM)
^ Memory Seat Module (MSM)
^ Navigation System (Japan export option)
^ Powertrain Control Module (PCM)
^ Radio (IRC)
^ Radio Amplifier (AMP)
^ Remote Function Actuator (RFA) Module
^ Rear Integration Module (RIM)
^ Road Sensing Continuously Variable Road Sensing Suspension (CVRSS) Module
^ Sensing and Diagnostic Module (SDM)
^ Steering Column Tilt/Telescoping Module (TTM)
^ PASS-Key(R) III Module (VTD)
Loss Of Class 2 Serial Data DTC:
Loss Of Class 2 Serial Data DTC:
Loss Of Class 2 Serial Data DTC (Part 1 Of 2):
Loss Of Class 2 Serial Data DTC (Part 2 Of 2):
Loss Of Class 2 Serial Data DTC:
Loss Of Class 2 Serial Data DTC:
LOSS OF CLASS 2 SERIAL DATA DTC
LOSS OF CLASS 2 SERIAL DATA DTCS MATRIX
The above charts represent a complete matrix of all Loss of Class 2 Serial Data DTCs. Use these charts as follows:
^ The top row of each chart indicates which module has lost Class 2 communications.
^ The left column of each chart indicates which module observed this Loss of Class 2 Serial Data, and internally set a DTC to identify this condition.
SIMPLE BUS INTERFACE (SBI) SERIAL DATA LINE
The Simple Bus Interface is used for serial data communication between the four door modules as well as the LH Front Power Window Switch. Electrical input and output devices within the doors are wired to the corresponding door modules; the power door locks, power windows, power mirrors, jamb switches, and cylinder switches are all controlled this way.