will not turn off

[dontbther]

my battery hit the hood when i went over a bump when i first got it not realizing it wasnt tied down.
i have a 1990 300zx n/a 2+0, stock
the battery had shorted against the hood for about 30seconds.
the car still ran fine but when i got home it wouldnt turn off.
all the accesories stop but the motor keeps running.
i have replaced the battery, alternator, ecu, ignition switch(electric side), most of the relays throughout the whole car even hidden ones behind the fuse box, fuel control computer behind the drivers seat.
i am at a complete loss. i have searched / posted on about 4 different 300zx forums im open to any suggestions thanks.
dontbther

Posts: 1
Joined: Mon Mar 12, 2012 5:53 am
Car: 1990 N/A pearl white,auto, , stock

[minus1]

My 1990 TT manual will run after the key is removed for about 5-10 seconds every time. Is that a normal thing?

Anyway, Mine would not turn of one time, it just kept running like you described, I had to pop the clutch with the brake on to kill it, then restart it and remove the key to "reset" it. If the 5-10 second run time thing is normal, maybe whatever system controls that is messed up.

[dontbther]

WHAT?????

[dontbther]

Anyone else????

[TTkickedin]

To minus1, if you have a turbo timer installe,d then yes it would be normal. But if you don't, both of you could be having the same problem but it can be from a variety of sources.

First off, pulling the EGI relay should be turning both of your cars off....

Second, make sure you guys have the newer style PTU, can cause a lot of problems if you have the old one, not sure if it would cause this though. this is the new one that you need:


then, here's the ignition circuit diagram for 300zx's. Check for shorts in the entire circuit.



Now, a problem i've seen is that someone has a short in the fuel injector harness, which then causes the ECU to malfunction and cause an issue like this. in this case it would be wise to find that short...



Then replace the ECU as well, as it can get damaged by the short in the injector harness.

[dontbther]

YesI have the new ptu. But I was thinking of switching it with my friends and see if that fixes it if not then ill start diving in to the wiring. Thanks

[minus1]

Thanks, i'll look into that. Mine did it twice this week where it wouldn't turn off. With mine, when i drop the clutch to kill it all of the electronic turn off like it would would normally. I have some other electric system gremlins(speedometer, seat belt light, power window switches) i will probably go to town with a multi-meter next week end. I don't think there is a turbo timer on mine, there is no display or adjustments i have found. There has been some "custom wiring" work done, It had neon lights and some stereo work. I'll post more if i figure something out.