Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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) |
|
Scan Tool Does Not Communicate with High Speed GMLAN Device |
| Communication Interface Module (OnStar), w/UE1 |
|
Scan Tool Does Not Communicate with Low 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 Seat Module (HSM), w/KA1 | 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 |
| Radio | 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 |
| Transmission Control Module (TCM) | High Speed GMLAN | Scan Tool Does Not Communicate with High Speed GMLAN Device |
| Vehicle Theft Deterrent (VTD) Control Module | Low Speed GMLAN | Scan Tool Does Not Communicate with Low Speed GMLAN Device |
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.