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.
VCU or VIU Reprogramming
Important: The new OnStar® component parts must be installed prior to the reconfiguration of the OnStar® system.
After replacement of the vehicle communication unit (VCU) or vehicle interface unit (VIU), the OnStar® system must be reprogrammed.
- Press and hold the Answer/End Button on the OnStar® Button Assembly until the System Status Light goes from solid GREEN to RED and back to GREEN again.
- Call the OnStar® Call Center at 1-888-OnStar1, select prompt 1.
- Give the operator the Electronic Serial Number (ESN) off the new VCU or the Station ID (STID) number off the VIU.
- Move the vehicle outside and let the vehicle run for 10 minutes.
- Press the OnStar® Call Center Call button and ask for a "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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