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Data Link References

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT: There are modules in this vehicle that communicate on a controller area network (CAN) serial data link. This CAN serial data link is not connected to the data link connector (DLC), and the scan tool cannot communicate on this link. Communication DTCs for this CAN Serial data link may be set by the module acting as an interface to the other serial data links. Refer to Data Link Connector (DLC) Schematics  for CAN serial data circuits. The following DTCs may be set when the interface module detects a loss of communication with a module on the CAN serial data link. Diagnose these DTCs as directed in the DTC Table:

CAN Serial Data - Powertrain Control Module (PCM) and Transmission Control Module (TCM)


For any other U codes or communication problems, refer to the table below for the correct procedure.

This table identifies which serial data link that a particular module uses for in-vehicle data transmission. Some modules may use more than one data link to communicate. This table is used to assist in correcting a communication malfunction between the control module and the scan tool. For the description and operation of these serial data communication circuits refer to Data Link Communications Description and Operation .

Data Link References

Control Module Data Link Type Diagnostic Procedure
Schematic Reference: Data Link Connector (DLC) Schematics 
Audio Amplifier Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Body Control Module (BCM) Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
CD Player (CDX) Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Digital Radio Receiver (DRR) Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Driver Door Module (DDM) Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Driver Seat Module Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Electronic Brake Control Module (EBCM) Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Energy Storage Control Module (ESCM) High Speed GMLAN Refer to Scan Tool Does Not Communicate with High Speed GMLAN Device 
Front Passenger Door Module (PDM) Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
HVAC Control Module Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Hybrid Control Module (HCM)
  • High Speed GMLAN
  • Class 2
Refer to Scan Tool Does Not Communicate with Class 2 Device 
Inflatable Restraint Sensing and Diagnostic Module (SDM) Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Instrument Panel Cluster (IPC) Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Electro-Hydraulic Power Steering (EHPS) Module High Speed GMLAN Refer to Scan Tool Does Not Communicate with High Speed GMLAN Device 
Powertrain Control Module (PCM)
  • High Speed GMLAN
  • Class 2
Refer to Scan Tool Does Not Communicate with Class 2 Device 
Radio Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Rear Seat Audio (RSA) Controller Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Rear Seat Entertainment (RSE) Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Rear Wheel Steering Control Module (RWSCM) Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Starter/Generator Control Module (SGCM) High Speed GMLAN Refer to Scan Tool Does Not Communicate with High Speed GMLAN Device 
Transfer Case Shift Control Module (TCSCM) Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Transmission Control Module (TCM) Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device 
Vehicle Communication Interface Module (VCIM) Class 2 Refer to Scan Tool Does Not Communicate with Class 2 Device