1984 Nissan 300ZX



December, 7, 2012 AT 8:34 PM

We have a 1984 Nissan 300 ZX with no spark. New ECU. Coil, Distributor and all associated hardware is new or good.
Turn on the ignition key and the ECU does not bulb test or give error codes unless you momentarily ground terminal 6 whereupon it will give codes (only AC errors) and then won't turn off when the switch is turned off. Dealer won't work on it and Nissan USA knows nothing and doesn't want to help.
Below is attempt to fix summary:
I will first list parts replaced:
ECM 3 times
LED assembly in the distributor
power transistor
cylinder head temp sender (from a trouble code)
EFI relay
timing belt

Things done and checked:
Checked output from dist to ECM, got the 360 signal and 1 other signal (assuming #1 cyl) with a good oscilloscope.
power to + side of coil
power to ECM
All grounds I could find with help from Alldata and an 84 300zx troubleshooting disc.
Condenser between coil from and ground @ dist base

Engine cranks normally, no spark from coil secondary. Checked and found no pulse on - side of coil.
Ignition on, ECM would not boot even with power on the proper pin at the ECM, unless a momentary ground of the #6 red wire at the ECM, from the EFI relay. Once powered up, turned screw to get codes, got 2 relating to the A/C. However, when ignition switch off, the ECM stays powered up (checked for 15 minutes) until ECM physically unhooked from harnesses. I have contacted the local Nissan dealer, and they disavow any knowledge and desire to tackle this, so in my shop it still sits.
If anyone there has any ideas, information or experience with this type problem, I sure would be grateful for help."
And will happily pay for solution

4 Answers



December, 7, 2012 AT 9:56 PM

I'm certainly not familiar with these cars but could htis be a theft relay problem or efi main relay problem not allowing spark as the anti theft goes right to the ignition switch. Just a thought here. There is also an ignition relay in teh fuse box if that's not working no power anywhere. I know because I 've got one on my mg and if it's bad the car won't get power like yours. Sometimes the simple things just get overlooked. I know been there lol.



December, 19, 2012 AT 1:25 PM

Replace the computer on under the glove box passage side door that the problem cause it have a 1984 nissan 300zx and it did the same thing hope this help u.



December, 22, 2012 AT 4:59 AM

I thank you for the responses.
The computer has been replaced three times just to make sure. The question that needs answering I guess is what (signal or lack thereof?) Would keep the computer from bulb testing when the key is turned on and not giving error codes unless a momentary ground on terminal 6 of the computer gets it to boot. It appears that the ignition switch is turning on everything that it should..
Help! (And thanks again)



February, 22, 2015 AT 8:33 PM

I have same issue with this and I started with changing my coil then distributor and it started up even when it was running I couldnt get it to give a light test and my guages wouldnt work but thought I would take it for a test spin just to see how it ran and drove about 5 feet and everything kicked on and ecu was lit up I was happy and then the next day it shut down on me there is where I found a relay strip above the fuse box on drivers kick panel one of them relays was going bad now doing good so far but bad miss in it and dies from time to time at idle im working on figuring that out now but check them fuses and relays first for me thats what it was I started banging the strip of them against the kick panel after I took the 2 screws out and after a few rappid wacks it started working thats a free easy to test lol if it does work replace them cause they will mess with u like they did me my car was setting outside for about 15yrs and I put a fuelpump in it drove it for 3 weeks and it died on me I got out and first thing was check for fire from coil and nothing and then I let it set for a year and put a distributor in it it fires right up now just has a miss and does good at 3,000 rpm and higher not so good from 2500 and less there I hope that helps u and that u might know how to help me with the missfire the ecu came up with 4 diff sensors idle controle I could see being 1 but fuel temp senc not sure head sens not sure cant rember what the other was sorry

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