1985 300zx anti theft problem

[Steph]

here is the deali drove through a "too deep" puddle with my 1985 300zxthe security system went off and now wont let the car start anymoremust be that cause i checked everything else...even changed the coil cause it didnt haven sparkssparkplugs are replaeced tooi even tried all the things they say to reset that damn thing but that doesnt want to work either...like locking the door, waiting for 30 sec and then unlocking itit seemed to shut it off but not really cause the light in the dashboard blinked againso can i possibly bypass the antitheft warning system...if yes how?please help..i cant spend hundreds of dollars for the shop and i dont want to get rid of the carso if anybody knows how to fix this problem please write as soon as possiblethanks Steph

[SHIFT_Z]

I drive a 89 300ZX, and sometimes the security system acts a little funny (blinking light when nothing is wrong) but I don't think that ever prevented me from starting it- Maybe talk to a Nissan dealer close to you?

[Steph]

the dealership told me to go home and they wont do anything to my car cause its too old...so im a little pissed at thatstill need information about bypassing the system and so onso if anybody knows how to do that or has other suggestions pleassssseeeee heeeeelp

[Eswift]

my old zx repair manual is 150 miles away, but let me try and think... all the sensors that tell the theft warning system something is wrong are activated by a circuit loop that is normally open, and becomes closed (current flows) when the hood, hatch, or doors are opened.

First thing, find all of these sensors and make sure they are dry ( i dont know how long ago this happened).

how deep was the puddle? could it have gotten to the door sensors or the hood one. i believe the door ones are pretty low on the B pillar, but you wo uld still have to have gone through a "puddle" about a foot deep.

if you dont have it, get the haynes manual and check out the security system wiring diagram.

dont know where the anti theft computer is, but you may have ruined it with the water.

when you close all the doors and hood and trunk, and lock the car from the outside, does the "security" light come on, and stay on?

cant diagnose your problem without you giving more info, buddy.

[Steph]

alrighty...the puddle was about a foot deep but i dont think that the sensors in the door triggered the alarm to go offthe car died on me right in the puddlethe incident was on christmas day and i made sure that the car is dried off before i even thought about doing anything to itthe anti- theft computer i found under the passengers seat..dried it off and that didnt work out so i went to the junkyard to get another oneso everything is dry and i guess that the security just doesnt want to let the car runeven bought a new coil cause it didnt have sparki tried all the tricks with locking and unlocking the doorthe alarm even went off when i tried to hold the button at the hood an locked the car and let go of the buttonlights went on and the dashboard light was blinking...after i unlocked the door and put the key in lights went back to normal but it still doesnt let me startas far as i remember the horn went off that day too but this time it didnt so i figured that it has something to do with the box that controls thatanyway...i just want to know if there is a way to bypass the security systemi have the book but cant figure out what might be wrongbut sure i look againbut thank you anyway for your helpi really appreciate thatStephy

[Eswift]

hmm...well when you try to start it, does the starter engage? i think all the dash indicator lights are supposed to go off when you have the ignition in the "start" position, do they all go off?

from the manual, is the theft horn the same as the normal horn? does the normal horn still work?

sorry i cant be of more help, but with this info maybe it can be tracked down.

also, check ALL the fuses and relays, could be something as simple as that, and i wouldnt be suprised if a puddle blew one of them.

[Eswift]

you could also try resetting everything by leaving the battery unlugged for a day...

[Steph]

thanks for all the advice...i know im a pain ..but well i really want to get it running againthe theft horn is the same i think but im not so sure about it and the fuses are alright...i checked that toomaybe youre right and i should unplug it for a while thanksif you know more just tell me

[Eswift]

well if you know the theft horn isnt working now, just try honking the normal horn. if it works, either the theft horn is different or the multipurpose horn is working and the problem is elsewhere.

again, when you try to start it, do you hear anything? starter? fuel punp?...everything but no spark?

if the starter isnt even doing anything, you have a few possibilities:

starter itself is deadstarter relaytheft warning starter relaytheft warning relaytheft warning horn relay (least likely)

i would say its the 2nd or 3rd to last relay i listed.

also make sure the battery and all connections, body grounds are good, might have gotten displaced

also make sure the battery is in tip top condition, it might have drained in the cold weather without any starts for such a long time,

when you turn on the headlights and try to start the car, do the lights dim at all>?

[Steph]

ok...the security system sets but has some kind of fault...i can engage the security system and it will "try" to go off if i open the hood or something...when i shut the system off using the key on the out side it does shut off however if i have the hood open the security light blinks...the engine cranks and with a little help from a charger it cranks good...power is being delivered to the starter coil however it is not comming out...and the coil is good. the next thing that i was going to try is removing the entire security system from the vehicle however i dont know how to do that and even so i dont know if that will work...any suggestions

[Eswift]

hmmm...could it be a distributor problem then?

have you tested for spark?

the actual theft protection system might disconnect the ground to the coil when it is tripped. thus, even if the coil is getting power on the positive terminal, it wont work if its not grounded. check to see if this ground is intact.

find that out and we'll take it from there

[Steph]

its not the distributor...it doesnt even come out of the coil...there is no spark not from the plugs not from the distributor and not from the coil.i dont know where the ground goesshould i just make another ground?

[Eswift]

if you dont already have one, and you can spare 20 bucks, go to radioshack or maybe even a store like menards/home depot and get a multimeter, preferably digital.

with this you can tell if the coil ground is actually grounded:

by pushing one wand to a conducting piece of the frame or engine block, and the other to the coil ground terminal.

If it doesnt hug right on zero volts, there is a bad ground, and that means thats your problem. you could then either track down the problematic relay, or you could just run another ground.

make sure you do this while somone is trying to start the car.

if the ground terminal shows 0V and the hot terminal shows about 13 V while someone is cranking, yet there is no spark, the coil itself is at fault.

hope some of this helps.

[Steph]

thanks ...ill try that...if that doesnt work ill get back to you okay?but do you maybe know how to just bypass that security system?i guess that would be helpfull too

thanks againSteph

[Eswift]

if i had a copy of the anti-theft wiring diagram here, i could tell you how to bypass it.

let me know how it goes.

[Steph]

http://300zx-twinturbo.com/cgi-bin/manual.cgi

thats a webpage where the whole manual is scanned in the wiring diagram is in there toomaybe with that you can tell me how to bypass itif that page doesnt work just go to :http://10w40.com/individual/100463.aspthanksSteph

[Eswift]

well i already have that manual, but i thought you had a Z31..? it is likely the wiring is significantly different because the z32 doesnt have a distributor, and has individual coil packs for each cylinder.

[Steph]

i tried grounding the coil that didnt work...im looking at the schematic and the only thing that it shows the theft warning system going to is the key switch starter and to the relay, and then to a theft warning control amp...(i dont know what that is) i did tell you that the engine turns over and power is getting to the coil however no power is comming out...i put a new coil in and also gave it a new ground and still nothing...im just about at a loss...thanks for you time and effort in helping me try and figure this out...i really do apreaciate it...joe

[Eswift]

well if you are sure you are getting +12V coming into the coil, and the coil isnt giving any output, there are two possibilities: either the coil itself is defective or isnt grounded properly. If you are sure it is grounded and is being supplied the correct input, it is probabaly defective.

how many wires are going to the coil? (excluding the hot output for the spark)

[Steph]

the coil is not defective ...ive tried three and this one is a brand new one...i know that the 12V is comming in and i know that nothing is coming out but i dont know how good tha ground is...ill have to check on that again...there is two wires going inone is hot one is not im gonna have to get back to you with more information after i checked it againthanks for the helpjoe

[Eswift]

yeah, its probably that ground connection is disabled by the theft relay...

[Steph]

so how do i enable the connection of the ground again thenjust making another ground?Steph

[Eswift]

yes, that would probably work. again, it would be better to find the relay and replace it, but if that isnt possible, an alternative ground should suffice.

[Steph]

didnt workim about to just give up

[Eswift]

if youve described everything accurately, it should be starting!

i would triple check those voltages on the coil with a multimeter...

[Steph]

i heard from another guy that it might be the emg or somethingthat little black box next to the computer that doesnt let the electricity flowcould that be it and do they have to match when i exchange them?you know what im talking about right?well let me know if that could be itother than that everything is orking i guesswell would know it better if the car would be runningthanks Stephy

[ucfz31s13]

If your not getting a spark from the coil, try checking the crank angle sensor. I had the same prob and tested the crank angle signal at the ecu and it wasn't getting any power. Replaced crank angle sensor and she was rolling again.

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