I have a 93 S10. I put an audio system in it a while back and noticed after the fact the mirror light cut on and off and sometimes even seem to beat with the music. I have taken it to several places to have them check it out and they say everything seems to be correct but it's obviously not. Oh and now my battery dies every two days if I don't drive it. Also recently noticed I get feedback in the system from revving the truck up. Anybody have any suggestions.