Mechanics

NISSAN 300ZX IGNITION SWITCH PROBLEM

1984 Nissan 300ZX

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)
coil
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

Avatar
Guest
December 7, 2012.



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.

Hmac300
Dec 7, 2012.
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.

Tiny
Dee8484
Dec 19, 2012.
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)

Tiny
Nolawyers
Dec 22, 2012.