Makes sense. Im unfamiliar with the NATS circuit so Im here learning as I go....

Thing is, Im not the most comfortable on buying a used ecu....

Will some pins need to be moved for the swap?

It should be fine, I bought a used ecu after mine went bad b/c of a bad IACV, and I havent had any problems.

Follow this link for NATS info, Mr. I'll Call You Later.

http://www.nicoclub.com/FSM/maxima/1999/EL.pdf

Page 297

To my understanding it's.....

Key sends OK signal to NATS

NATS sends OK signal to ECU

ECU turns on the fuel pump.

In the pinout diagrams there's a pin for NATS on the 99 ECU's but not on the previous years... And I want a 96 ecu for tuning purposes

Locksmith came and reprogrammed it for free since it was under warranty. He also cleared some error codes that the admitted he didnt clear the first time.

@Kev: My bad. Sihts been super hectic with me. Hard to find a gram of free time. Im getting foreclosed and in the middle of a last minute move....

Will call you as soon as I can.

I'm just yankin your chain, yeah call me when you can, I have some questions about some of your mods.

I'm glad you were able to get your car running again at no additional cost to you.

VQ'rInWLA, sorry for you. But the mystery remains, what is happening? Are you sure your not accidently trying to use a different key? Do our '99 keys really 'go bad'?

My immobilizer shut me down a few years ago. I was towed to my dealer and was totally ripped off of course. At the time I was convinced that I put one of my Oldsmobile ignition keys into my Max ignition, causing the stupid immobilizer to kick in (that is the intent of the system I am told). So now I use two different key rings!

I do not understand why Nissan would shut down my ride if some bozo puts his dumb bogus key in my car's ignition to steal it? Just do not start the car! Period! Do not shut me down hundreds of miles from home, with no way to 'reset' the condition even though I have the proper key!

Can anyone explain what the theory is behind this "immobilizer" other than to cause lots of pain to innocent owners?

Is there a general lifespan that these transponders have? I'm driving a 99 SE-L and am looking to avoid any possible issue in the future

No I only have my ignition key on mine. When I fired it up, it idled then died right away. So it kicked in then. Turned it into acc after and saw the damn red light....tried the other key locksmith made....red light. It forgot its programming is pretty much what happened.

99s are the first generation of the immobilizer for the A chassis so I figure this is one of those kinks that needed to be worked out.....

My chassis only has 60k on it. Pretty young for it to go bad if you ask me. Just be sure not to wet your key or get it magnetized.

I wouldn't measure electrical parts in terms of mileage, your keys were around 11 years old when they went out, think about what you were doing 11 years ago.... yeah...

I know but I figured Id throw that in there since I was picturing the number of times the car was cranked over. And keys were only 8 months old....

did anyone swap any earlier ecu into there 99? if so how did ya do it was it the same pins? anything have to be altered?

This has been covered alot.. You have to swap around a few pins and youre good to go... Only altering is the pin layout..

All you have to do is replace the fuel pump relay with a jumper. The power through the relay is switched by the ignition switch, so it only gets power when you turn the key on. Relay is located behind the driver side kick panel. The relevant wires are black/white and black/yellow.

Do you have first hand experience with your advice? Were you immobilized and your remedy fixed it?

I did it to my own car. As soon as I got it home after buying it, I got locked out by the NATS.

I swapped in a 95 auto ECU, but it threw emissions and tranny codes right away, so I swapped it back to my original ECU. Then I tried to find a way to activate the relay with power off of a different pin, but didn't get far before I thought to check to see if the power to the relay was switched or not. It was, which meant that I wouldn't drain my battery or burn out my pump. I used spade terminals on my jumper so that i wouldn't have to chop up the harness.

You got 99 problem and a B**ch ain't one.........

Wow!
Brilliant!

I wanted to ask abt this, so if have issues with being immobilized, you can simply jump 2 wires and don't have to worry abt reprogramming ur key and computer again? Did u ever run into any issues after this rewire?

Als wat wires are you rewiring?

If I understand this correctly you are connecting the black/white directly to the black/yellow wire?

I don't think this jumper will do it. When immobilized, the ECU does not send the pulses to the fuel injectors.

It turns out that doing this didn't actually fix anything. The immobilizer stopped acting up, by coincidence, exactly when I did this. Later on I got immobilized again even though I had my fuel pump jumpered.

On the other hand, this puts to bed the myth that the immobilizer works by disabling only the fuel pump.

Many people oten to say that NATS cuts off the fuel to the engine. This is a true but vague statement. It allows for mis-interpretation of exactly what is happening.

If someone wants to experiment, the NATS unit in the steering column sends a signal to the ECU on pin 17. I don't know if pin 17 on the ECU has to be ground or 12 volts to allow the car to start. Whatever the voltage is when the car is immobilized, it would obviously have to be the opposite for the car to start.

Thanks for clarifying, I have a 99 that I have been trying to figure out, I put it into ignition, it cranks and starts up, stays on for abt 3 seconds and than shuts off and red security light than comes on solid, this would conclude that it Is immobilized correct?

I though it should not start even for a second,

Same thing happened to me not too long ago. However, I'm not entirely sure why mine immobilized. Had to tow mine to the dealership and had them reset/override the computer. Then started no problem without the stupid annoying light. You could do it yourself if you have a nissan scan tool, but I believe the dealerships usually are the ones to carry them. Also, the dealership only charged me $120 for it. So it wasn't that big of a deal.

Finally found a locksmith that would would come out to my house that thought he could reset the NATS on my car. http://www.popalock.com/fran.../gain..._locksmith.php
He was able to reset the system and get my car running and only charged $75, I am extremely happy!

Thanks again for this fix!

I understand SnapOn makes a diagnostic tool named Solus that (with the right Nissan module) can reprogram Nissan keys.. If you can't find a locksmith or dealer to do a key resync, it may be an alternative.

I've accidentally immobilized two of my 99 models. I have read that trying (unsuccessfully) to start a 99 model with the door open (after 3 tries) sets up a condition that can trip the immobilizer. In both cases when I immobilized my 99 models, I didn't know at the time to keep the driver's door shut while working through a start up issue. So I stopped trying to run the starter (for a compression test or the likes) with the door open and so far I've not accidentally immobilized either of my 99 models.

sorry for the old bump~ but can AAA reset the NAT? My issue is, car is immobilized but I have two working keys (no damage).