Principles of Operation: Subwoofer
WARNING: This page is about a different car, the 2007 Lincoln Mark LT and 2007 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
The subwoofer speaker is powered from a separate subwoofer amplifier. The enable/clip circuit carries out 2 functions: to turn the subwoofer amplifier on, and to indicate to the audio unit when the subwoofer output distortion signal reaches an excessive level. The audio unit then reduces (clips) the audio output signal to the subwoofer amplifier.