Vehicle Interface Unit: Notes
NOTE:
DO NOT exchange OnStar® Vehicle Interface Unit (VIU), or Vehicle Communication Units (VCU) from other vehicles. Transfer of OnStar® components from other vehicles should not be done. Each OnStar® component has a unique identification number. VIU has a 10-digit specific Station Identification (STID) and VCU has a 11-digit specific Electronic Serial Number (ESN). These identification numbers are used by National Cellular Telephone Network and OnStar® systems, and are stored in General Motors vehicle history files by VIN.