Hello everyone,

A friend of mine is having issues with her '01 Maxima. I'm a backyard mechanic and she doesn't have the money to take it to a real mechanic, so I'm helping her out as much as I can, but I'm running into issues.

It started with the P0505 code, so I removed, cleaned and re-installed the IAC. That solved the issue temporarily but, not surprisingly, 3 months later the car wouldn't start. My ODB reader was unable to even communicate with the ECU, so I pulled it, and sure enough, the IAC chip was fried. I replaced both the IAC and the ECU (and tested the TPS) and also swapped the immobilizer chip and chip reader with a set that matched the ECU.

Unfortunately, the problem persists. After installing everything today, the car wouldn't start and I was STILL unable to read the ECU at all. The "Security" light stays illuminated while trying to start, so that leads me to believe that it might be an immobilizer issue, but would that restrict me from even reading the ECU?

Any advice would be GREATLY appreciated.

 

Hmm are u sure the new ECU is a good one? Check fuses..especially the ones in the the lower dash..look for the ENG CONT fuse.

 

I have put this document together for people like you: https://drive.google.com/file/d/0B6O...ew?usp=sharing
Hope it helps. Let me know if it doesn't.

 

When you swapped the ECU, you no longer had keys that matched the codes stored in the replacement ECU. Swapping the chip reader doesn't really have any bearing on immobilizing the car.

 

I'm still unsure as to whether swapping the chip reader mattered at all, however I DID swap the chip in the key itself (the little tab on the key) to the one mated with the ECU, so my understanding is that it should work fine...

 

The new ECU was numbers-matching with the old one, so I'm not concerned about compatibility. I pulled the cover off before installation and everything seemed in order (the AIC chip looked perfect and original), but that's obviously not a guarantee. i did not check the interior fuses, so that will be the first thing I look at tomorrow. Thank you very much for the advice!

 

Thanks Maxiiiboy, that really helps understand the issue more fully. Unfortunately, I'm still not getting anywhere...

The problem is, the ECU has been replaced with a good condition used one, but the car still won't start and my ODB2 scanner can't even detect it. Although I replaced the chip in the key with one matching the new ECU, the security light doesn't turn off while cranking and so I'm thinking it might still be an immobilizer issue. So, my new question is as follows;

Will the OBD port function properly if the immobilizer isn't de-activated?

Maybe the chip in the key is faulty or something? I'm trying to determine if there is multiple underlying issues or just the one.

Thanks again for all the help everyone.

 

When you replace your ECU, you have to re-initialize NATS. Quoting directly from the FSM, page EC-89:

• When replacing ECM, initialization of NVIS (NATS) system and registration of all NVIS (NATS) ignition key IDs must be carried out with CONSULT-II using NATS program card. Therefore, be sure to receive all keys from vehicle owner. Regarding the procedures of NVIS (NATS) initialization and NVIS (NATS) ignition key ID registration, refer to CONSULT-II operation manual, IVIS/NVIS.