Vehicle Communication Unit: Notes
NOTE:
Never exchange OnStar(R) vehicle integration units (VIU) or vehicle communication units (VCU) from other vehicles. Transfer of OnStar(R) components from other vehicles should not be done. Each OnStar(R) component has a unique identification number. VIU has a Specific Station Identification (STID) and VCU has a specific Electronic Serial Number (ESN). These identification numbers are used by National Cellular Telephone Network and OnStar(R) systems, and are stored in General Motors vehicle history files by VIN.