The RNS 315 navigation system map update is typically because the system uses proprietary copy-protected SD cards . While the official V.4 version is older (newer versions like V.12 are available), the core update process remains consistent. The Standard Update Path
: Official or genuine replacement SD cards are modified by the head unit during installation, marking them as "used" so they cannot be reused in another vehicle. download RNS 315 v.4 Map Update - SD Card