I have a 2004 350z with 83k miles on it and I have never had any issues at all out of it. Recently I’ve been having a strange electrical issue. I first noticed the other day when I went to lock my car from the key fob and instead of it making one quick beep like it should, my horn just came on and wouldn’t go off. The only way I got it to go off was starting the engine. A few days later when I went to leave for work, the car came on like normal but wouldn’t start. It would turn over just not start. After digging a bit deeper I’ve noticed there are multiply electrical issues. Even when I take the key out completely, it doesn’t seem to shut off completely. For example I can take the keys out and leave it alone for an hour and come back to my car and the windows will roll up and down although the car appears to be off. Also the lights on the gauge cluster flicker. The seatbelt and battery light are the main two that flicker. When it does this you can hear a light electrical humming or a buzz from under the hood. Anyone had similar problems or know maybe where I couldn’t start diagnosing it?

 

This isn't a common problem with Z33s, but do pop up occasionally. Have you run a scan to look for ECM or BCM codes? Post up the codes you find in memory.

 

It initially through a code when I first had the problem but once I turned the care off and started it again the check engine light was off. I was gonna have it checked for codes but it has came back on since then.

 

Start by doing a scan of any codes held in memory. Post up what they are, even if a CEL isn't on.