Data Link References

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2005 Isuzu Ascender, 2005 GMC Envoy XUV, 2005 GMC Envoy XL, 2005 GMC Envoy, and 2005 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

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 Link Connector (DLC) Schematics
Body Control Module (BCM)	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Communication Interface Module (OnStar®), w/UE1	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Digital Radio Receiver (DRR), w/U2K	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Driver Door Module (DDM)	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Driver Seat Module (DSM), w/AAB	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
DVD Player	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Electronic Brake Control Module (EBCM)	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Endgate Module (EGM), for XUV	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Engine Control Module (ECM), w/5.3L	High Speed GMLAN Class 2	Scan Tool Does Not Communicate with High Speed GMLAN Device
HVAC Control Module	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
HVAC Control Module - Rear Auxiliary	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Inflatable Restraint Sensing and Diagnostic Module (SDM)	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Instrument Panel Cluster (IPC)	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Liftgate Control Module (LGM), except XUV	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Passenger Door Module (PDM)	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Power Roof Module (PRM), for XUV	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Powertrain Control Module (PCM), w/4.2L	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Radio	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Theft Deterrent Control Module (VTD), w/BAE	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Transfer Case Shift Control Module (TCSCM), w/4WD	Class 2	Scan Tool Does Not Communicate with Class 2 Device (4.2L w/o Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (4.2L w/Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (5.3L)
Transmission Control Module (TCM)	High Speed GMLAN	Scan Tool Does Not Communicate with High Speed GMLAN Device