Before I start my most favourite activity of all time.....chasing automotive wiring shorts, is this a common 300zx fault that's come up before? Basically i have to pull the fuse when I park because the two tail brake lights and spoiler light are hard on as soon as there is 12v at the battery terminals. Or have I just gone full retard and not realised the brake lights still work with IGN/ACC off and it's probably just a stuck micro?
Often a damaged brake light switch on the pedal. Little plastic insulator gets damaged and causes the short.
Chances are the brake light switch will be okay ....... the little green bumper on the brake pedal arm will have gone brittle, shattered, and fallen out allowing the switch to activate without the pedal being depressed. And the answer to your question is ...... YES, it's a very common occurrence on the zeds as they age
