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.
Vehicle Communication Unit/Vehicle Interface Unit (ONSTAR®)
After replacement of Vehicle Communication Unit (VCU), Vehicle Interface Unit (VIU) or Vehicle Communication Interface Module (VCIM), OnStar® system must be reprogrammed. Call OnStar® call center and follow operator instructions. Be prepared to give operator Electronic Serial Number (ESN) of VCU (2.6)/VCIM (F1) and/or Station ID (STID) number of VIU (2.6)/VCIM (F1).
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Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.