PAC OS-2C-CTS OnStar Radio Replacement Interface for Cadillac CTS 2004 and Up General Motors OnStar Interface for Cadillac CTS/SRX Class II circuitry will not disable vehicle data bus even if interface loses power On Star active LED and Ignition on LED Provides +12v switched accessory output Mute output to either mute the aftermarket radio or to turn if off when On Star is active Replaces factory radio in 2004-Up Cadillac CTS/SRX while retaining OnStar Plug & play-no cutting or splicing into factory plug Communicates directly with OnStar module to prevent false triggering & eliminating unwanted audio noise On-board amp will drive two 4-Watt speakers in stereo Use with existing factory speakers or external speakers