Nistune Forums

Recently installed Nistune in a P11 ECU (3J400), but have very annoying problems with NATS, which makes the car undriveable from time to time.
If the keys/NATS are synced it will work ok, until the battery is disconnect it starts all over again.

This all started after Nistune was installed, before this the car/Nats worked fine.


Has anyone else had/seen this problem ?

Or, are there any P11 ROMs available that have NATS disabled which I can try ?

-Eric

Hi Eric

Perhaps there is a problem with the ROM file. Perhaps if you can redownload if possible and email that through I'll repatch and you can put in the board again. Even if I give you a non-patched ENT to put in the board to see if consult code causes the problem or if its the board memory mapping itself - however its its the first I've heard of this issue with P11

Nistune board copies the ROM image from EEPROM and runs with that in RAM until powered off. We are mapped from 0x4000-0xFFFF in the ECU. Unless ECU is storing something NATS related in that area I dont know of

There are no P11 ROMs with NATS disabled. Best we can do otherwise is try and reprogram the EEPROM on the ECU to remove it but only been successful with one other model vehicle doing this at the moment (looking into others). I'm trying to remove NATS from a N15 SR20DE ECU today

Matt, as soon as the car is in again, I will do some more troubleshooting and re-read the original ROM and send it to you.

I'm not very familiar with NATS (or how to kill/bypass it), but I've looked at the schematics of the P11 and it looks like hotwiring one particular relay should do the trick of at least being able to start the car..(the check engine light will be flashing though)
...unless there is some code inside the ECU that cripples the car

-Eric

NATS in summary:

- Key is coded with NATS key (by Nissan dealer)
- Key communicates with IMMU (Immobiliser unit) the code
- IMMU is connected via a single bidirectional serial line to the ECU
- ECU has the same code as NATS stored in 93C46 EEPROM chip on a small NATS board (S15 ADM, EDM/S14 EDM/N15 EDM) or by itself (K11/P11)
- Codes are compared and there is a go/no go inside the ECU which will
(a) Trigger NATS fault code (there are 6 of them #3 is the one I see on my bench)
(b) Flash ECU CEL
(c) Limit injection time so that car cannot start

When the Nissan dealer recodes the key, the Nissan consult with a NATS card is connected to the ECU and the ECU is then recoded. There would a a consult command to NATS reprogram along with a key. This would then perform operations to reprogram the EEPROM with the new code and match the key. So there is a consult command in there that I need to find and intercept to find where it programs the EEPROM. Next check is from the DTC codes raised for NATS (located these on S15 previously) find where it is raised and that is the NATS code where the flags are set to indicate immobilise. So its possible to modify the ECU code to prevent immobilisation but hasnt been done before. We normally just put in a non-NATS ECU program into the board where possible (eg using JDM non NATS compatible ROM images)

With regards to the EEPROM there is a program which modifies the EEPROM for a particular vehicle, and I've used this and can confirm it works. It so far only works on that model ECU as I've tried S15 and it didnt work. Still to try others to see if it works with those. I suspect the reprogramming is different and I dont know how the author found out how to circumvent the EEPROM since they support all other vehicles too

Today I had the car in again and it had all sorts of ECU/NATS problems.
The consult-connection had sudden communication drops or it would go into failsafe for no reason.
I could sync keys, but after a few minutes a new NATS failure would come up.
So I figured it must have been something in the 3J400 ROM (corruption of some sort).

I reflashed the board with a 3J800 image and resynced NATS/keys and all seems well now.

Let's hope the gremlins keep out now

Didnt get another 3J400 ROM image at all?

> Didnt get another 3J400 ROM image at all?

No, the owner was using a stock 3J800 ECU for the time being, as the car was undrivable with the Nistuned (3J400) ECU.
I first reflashed the Nistuned ECU again with the 3J400 ENT image you send me previously, but it had the same problems
So I tried a 3J800 ENT instead just for testing purposes and all worked fine all of a sudden, so I left it that way.
The owner needed the car back (daily driver), so there was no option for further troubleshooting of the 3J400 ENT issues.

-Eric