Data Link References

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. Some modules may have multiple communication circuits passing through them without actively communicating on that data link. This table is used to assist in correcting a communication malfunction. For the description and operation of these serial data communication circuits refer to Data Link Communications Description and Operation .

Control Module	Data Link Type	Diagnostic Procedure
Schematic Reference: Data Communication Schematics
Body Control Module (BCM)	High Speed GMLAN Low Speed GMLAN	Scan Tool Does Not Communicate with High Speed GMLAN Device
Digital Radio Receiver (DRR), w/U2K	Low Speed GMLAN	Scan Tool Does Not Communicate with Low Speed GMLAN Device
Electronic Brake Control Module (EBCM)	High Speed GMLAN	Scan Tool Does Not Communicate with High Speed GMLAN Device
Engine/Powertrain Control Module (ECM/PCM)	High Speed GMLAN	Scan Tool Does Not Communicate with High Speed GMLAN Device
Heated/Vented Seat Module (HVSM)	Low Speed GMLAN	Scan Tool Does Not Communicate with Low Speed GMLAN Device
HVAC Control Module	Low Speed GMLAN	Scan Tool Does Not Communicate with Low Speed GMLAN Device
Instrument Panel Cluster (IPC)	Low Speed GMLAN	Scan Tool Does Not Communicate with Low Speed GMLAN Device
Inflatable Restraint Sensing and Diagnostic Module (SDM)	Low Speed GMLAN	Scan Tool Does Not Communicate with Low Speed GMLAN Device
Passenger Presence System (PPS)	Low Speed GMLAN	Scan Tool Does Not Communicate with Low Speed GMLAN Device
Power Steering Control Module (PSCM)	High Speed GMLAN	Scan Tool Does Not Communicate with High Speed GMLAN Device
Radio	Low Speed GMLAN	Scan Tool Does Not Communicate with Low Speed GMLAN Device
Rear Differential Clutch Control Module (Transfer Case Control Module)	High Speed GMLAN	Scan Tool Does Not Communicate with High Speed GMLAN Device
Rear Seat Audio (RSA) Module	Low Speed GMLAN	Scan Tool Does Not Communicate with Low Speed GMLAN Device
Remote Function Actuator (RFA)	Low Speed GMLAN	Scan Tool Does Not Communicate with Low Speed GMLAN Device
Rollover Sensor (ROS)	Low Speed GMLAN	Scan Tool Does Not Communicate with Low Speed GMLAN Device
Theft Deterrent Module (TDM)	Low Speed GMLAN	Scan Tool Does Not Communicate with Low Speed GMLAN Device
Transmission Control Module (TCM)	High Speed GMLAN	Scan Tool Does Not Communicate with High Speed GMLAN Device
Vehicle Communication Interface Module (VCIM) (OnStar), w/UE1	High Speed GMLAN - pass through only Low Speed GMLAN	Scan Tool Does Not Communicate with Low Speed GMLAN Device