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. 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 .
| Control Module | Data Link Type | Diagnostic Procedure |
|---|---|---|
| Schematic Reference: Data Link Connector (DLC) Schematics | ||
| Audio Amplifier (AMP), w/UQ7 and Y91 | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Body Control Module (BCM) | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Communication Interface Module (OnStar®), w/UE1 | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Digital Radio Receiver (DRR), w/U2K | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Driver Door Module (DDM) | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Electro-Hydraulic Power Steering (EHPS) Module, w/HP2 | High Speed GMLAN | Scan Tool Does Not Communicate with High Speed GMLAN Device |
| Electronic Brake Control Module (EBCM) | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Energy Storage Control Module (ESCM), w/HP2 | High Speed GMLAN | Scan Tool Does Not Communicate with High Speed GMLAN Device |
| Engine Control Module (ECM), w/LLY |
|
Scan Tool Does Not Communicate with Class 2 Device |
| Generator Battery Control Module (GBCM) | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| HVAC Control Module | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Hybrid Control Module (HCM), w/HP2 |
|
Scan Tool Does Not Communicate with Class 2 Device |
| Inflatable Restraint Sensing and Diagnostic Module (SDM) | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Instrument Panel Cluster (IPC) | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Memory Seat Module (MSM), w/AN3 | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Passenger Door Module (PDM) | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Powertrain Control Module (PCM) |
|
Scan Tool Does Not Communicate with Class 2 Device |
| Radio | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Rear Seat Audio (RSA) Controller, w/UK6 | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Rear Seat Entertainment (RSE), w/U42 | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Rear Wheel Steering Control Module (RWSCM), w/NYS | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Remote Playback Device - CD Player (CDX), w/U1S | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Starter/Generator Control Module (SGCM), w/HP2 | High Speed GMLAN | Scan Tool Does Not Communicate with High Speed GMLAN Device |
| Transfer Case Shift Control Module (TCSCM), w/NP1, NP8 | Class 2 | Scan Tool Does Not Communicate with Class 2 Device |
| Transmission Control Module (TCM), w/M74 |
|
Scan Tool Does Not Communicate with Class 2 Device |
NO RELATED
Use the Manual With the Right Hardware
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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.