12v system

okay so my tail lights arent working...neither are my gauge lights /cigarette lighter/ radio and such.....i had Best Buy replace my head unit( under warranty)....they told me that it was something wrong with my 12v system..but they got my radio 2 work...anybody know anything about that?

All cars operate of a 12 volt system. It has been that way for a long time. That just means that the voltage on your electrical system is 12 volts off the battery and should be about 12 volts everywhere in your electrical system (subtract a minor voltage drop due to the normally low resistance in wiring; anything with resistance creates a voltage drop). Maybe they mean you are not getting 12 volts at the device; if it is too much lower than 12 volts, it would indicate a higher than normal resistance in some component such as the wiring (beginning to go bad) or bad ground, or maybe something such as your alternator or battery.

hmm.. that sounds remarkably familiar. Somehow when I replaced my HU I blew the guage lights fuse and earlier I blew the cigar/clock fuse (fyi: it's also for your horn). Make SURE you replace the gauge fuse ASAP if your guages aren't working (speedometer will work though) because they control your alternator's output. You WILL kill your battery if you don't.

::edit:: actually, that may be why your tailights don't work... I know my blinkers stopped working as my battery was dying.