2009 xterra ticking ???
 

Just bought a 2009 xterra and I have a ticking noise that sounds like behind the stereo. It ticks regardless if it is running or the motor is off. It will do it until the battery is dead. For some reason when it ticks the stereo dims when the ticks happens and when you turn the headlights on it stops ticking. Kind of stumped me. Any ideas would be appreciated.

I suggest you start off by checking all the fuses and wires. Eliminate as many possible issues first.

This sounds like you have something wrong with your stereo(probably a frayed wire or a short somewhere).

Yes this may be the wiring or fuses issues because as you told the noise stops when you turn on the head lights. So you should check the whole dash wiring and fuses and also the stereo plugs. Good luck.