i came across a violet/yellow wire with a single plug that connects to the back of the factory stereo. what is it? what does it do?
2001 sebring ltd

 

That's the PCI bus from the body computer. One thing it does is monitor whether the convertible top is up or down and if the top is down, the configuration of the audio is changed slightly. Also, the stereo is, to a certain extent, self-diagnostic, for instance, if a speaker is shorted out, it senses that. If it finds a fault, it sends a fault code to the body computer, and that fault code can be read by the dealer using his equipment. You lose all that when you put in an aftermarket stereo.

 

DAM, who knew! lol