OnStar Vehicle Communication Unit (VCU) Replacement: Notes
IMPORTANT:
Both the vehicle interface unit (VIU) and the vehicle communication unit (VCU) have a specific set of unique numbers that tie the module to the vehicle where the module resides. These numbers, the 10-digit station identification and the 11-digit electronic serial number, are used by the National Cellular Network and OnStar to identify the specific vehicle. Because these numbers are tied to the vehicle identification number (VIN) of the vehicle, do NOT exchange these parts with those of another vehicle.