Pac OS-2 Onstar Interface for 03-05 Non Bose Cars OS2 The OS-2 uses a Data Link Controller chip (DLC) that is specifically designed for connecting to GM's Class 2 data bus. Safe & Sound Class 2 circuitry will not disable vehicle data bus even if interface loses power. When OnStar is active, the OS-2 will keep OnStar on, even when the key is removed and the door is opened. OnStar will turn off when the call is complete. OnStar active LED and Ignition on LED for visual indication. Provides +12v switched accessory output. No more searching for switched +12v in fuse box or kickpanel. Smart Sense Mute output to either mute the aftermarket radio or to turn it off when OnStar is active. Retains door chimes when used with optional CM1 chime module. New radio will operate with the vehicle RAP (Retained Accessory Power) system. The radio stays on after the key is turned off and stays on for aproximately 10 minutes or until a door is opened.