The Nissan shop manual has a complete wiring diagram, they can be found on e-bay.
try ebay, search 1985 300zx for the Nissan Service Manual, I have the 1986 manual , it contains the wiring diagram
need diagram for wiring for 1986 transam
need diagram for 1986 Nissan truck alternator
I need the wiring diagram on a 1986 Chevy silver ado dual fuel tanks
location and wiring of the horn relay
Bikebandit.com
look on eBay for 1986 Nissan service manual
Autozone
A wiring diagram can be found as a print out from an automotive store. A person can also get it from the cars maintenance manual.
the only wiring diagram i have found on line for free so far is at autozone.com
Its probably has a vaccume hose leak.