To turn off the sensor light you disconnect a wire under the dash. On my 86 2+2 it was just above the hood release. You'll see a big bundle of wires there and a single wire with a connector in it. On mine there is a label on it that says something like "O2 sensor ... reset at 30,000 and 60,000 ... disconnect at 90,000" Bob
Honestly just buy a chiltons repair manual. It has everything you need to know about the car. It covers 1970-1988 Nissan z's or zx's
if you send me a email I will send you a picture
try ebay, search 1985 300zx for the Nissan Service Manual, I have the 1986 manual , it contains the wiring diagram
http://www.300zx-twinturbo.com/cgi-bin/manual.cgi
The nissan owners club is a good place to find cheap parts
http://www.300zx-twinturbo.com/cgi-bin/manual.cgi look through the service manual.
Answer...everyone should have a manual for their vehicle(parts store or dealer), and a local library should have professional shop manuals available in the REFERENCE section for free...make copies of the appropriate sections...read up and good luck :) To the person who wrote that... there IS NO manual for the 1990-1996 Nissan 300zx in ANY library. The SERVICE manual can be found online all over, but it's the original SHOP manual. (you know, for Dealers?)As a current 1990 300ZX owner, I have scoured the forums, the web, and other Z owners, and they all agree that NO user(friendly) manual was ever produced. (way to go Chilton and Haynes... Boo on you)Before answering a question with such a broad-spectrum (and vague) answer, please know what you are talking about.
Refer to your manual. Buy a Chiltons.
Using a scanner with a scope, you can view the output wave of the sensor as you crank the engine.
With filter: 3-5/8 quarts Without filter: 3-1/8 quarts Source: Nissan 300zx Service Manual
mass airflow sensor of head tip sensor could also be catalytic converter
English Online Manual for 300ZXThis online manual is in English:http://www.300zx-twinturbo.com/cgi-bin/manual.cgi