test light will be good to use.. i dont know whats the wires in a zx since i hard wired everything but...
USUALY

red- acc
yellow - const
ground = chassis!!

 

I have some pdf files for the wiring diagrams for an '83. I'm not sure how close they are but I'll email them to you if you'd like to try and interpret them. They took me a little getting used to since they ar ein a littledifferent format than I'm used to.

 

https://www.zdriver.com/forum/showth...t=10598&page=1

 

I had to make a new constant from the fuse box, because every time I turned on the lights with the stock constant it would turn off and come back on when I shut them off. but the best way is probibly to run a wire to the box that conects directly to the battery and put a fuze in it.

good luck, this was the hardest stereo install I have ever done.