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 (On-Star(R))
After replacement of Vehicle Communication Unit (VCU) or Vehicle Interface Unit (VIU), OnStar(R) system must be reprogrammed. Press and hold Answer/End Button on OnStar(R) button assembly until system status light changes from Green to Red and back to Green again. Call OnStar(R) call center at 1-888-OnStar1 and select prompt 1. Give operator Electronic Serial Number (ESN) of new VCU or Station ID (STID) number of VIU. Move vehicle outside and let vehicle run for 10 minutes. Press OnStar(R) call center call button and ask for "Reconfiguration".
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.
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