Principles of Operation
WARNING: This page is about a different car, the 2008 Ford RV Cutaway, 2008 Ford Econoline, 2008 Ford E450 Super Duty, and 2008 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
The audio unit can be powered up when the key is in the RUN or ACC position. The audio unit provides audio signals to the speakers, thus producing sound.
The audio unit directs the audio signals to the speakers through separate positive and negative circuits for up to 4 audio channels (depending on configuration): LH front, RH front, LH rear and RH rear. The audio unit provides internal circuit protection for shorts to ground, shorts to voltage or shorts between any output circuits.
The radio noise suppression equipment reduces interference transmitted through the speakers by the engine ignition and electrical systems.