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.
High Speed GMLAN Serial Data Line
The GMLAN serial data communications circuit on this vehicle is in a linear topology. The following modules are connected to the link, in order from data link connector (DLC) to the end of the linear configuration:
- The instrument panel module (IPM)
- The electronic suspension control (ESC) module, with F85
- The communication interface module (OnStar), with UE1
- The dynamic headlamp leveling (DHL) device, with TR7
- The electronic brake control module (EBCM)
- The transmission control module (TCM)
- The engine control module (ECM)
The distance sensing and cruise control (DSCC) module, with K59 option, it is connected to the high speed GMLAN bus through splice pack SP100. Refer to Data Communication Schematics for more information.
The OnStar module doesn't functionally communicate on the high speed GMLAN bus. It is connected to high speed GMLAN bus for remotely diagnostic purposes.
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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.