Facias And audio harnesses Available here. Whether you are running important errands or have a long commute to work, a well-functioning audio system is important to listen to your favorite tunes, the weather or the local news. To help keep the stereo system properly wired and in place, facias and audio harnesses are important. These should protect the components of the audio system properly so that they are not jostled around when you hit a bump or have to drive on a rough road. High-quality facias and audio harnesses work hard to ensure that the vehicle’s stereo system remains in good condition and does not slip and slide around while the vehicle is in motion.