How to match ignition key and remote control key on Nissan with scan tool?

1. Key initialization 

Initialize the car key under following conditions: 
(1) For earlier models, whose ECU do not  support C/U INITIALIZATION, and Scan tool 
can only read DTCs and clear DTCs from NA TS. For such models, the car key can be 
initialized without decoder.   
Operating steps: turn the ignition key to ON  position and wait at least 5sec, then pull out the key and wait at least 5sec, after that, t he ignition key will be initialized automatically. 
(2) For newer models, the initialization  should be performed with scanner when the 
following conditions meet: 
(2.1) If the BCM is replaced, to initialize  all ignition keys or door keys by decoder.   
(2.2) If replace a used ECM, to in itialize all keys by decoder.   
(2.3) If replace a new ECM, just turn the i gnition key on and wait 5sec and then turn off, the ignition key will be initia lized automatically. If the engine can’t be started, then the ignition key shall be initialized by decoder. 
All existed ID numbers will be cleared as long as initialization performed. Therefore, it is necessary to register all the keys again.  Otherwise, the engine  can’t be started, and "DIFFERENCE OF KEY" or "LOCK MODE  will be appeared on the display of scanner 
when performing scan on OBD."   
Before initializing the car key, the PIN codes shall be obtained. Following is the 
explanation of PIN codes: 
PIN codes can be separated into fixed code and random code, which can be differentiated 
from the printed characters on label  which sticked on NATS control unit. 
Fixed code: if the label is prin ted with characters [A] or no  characters, then the PIN code is a fixed code. 5523 is default, which is mainly applied on some 2000-2004 models, such as Cefiro A33, SUNNY and the other common models.   
Random code(4 digits): can be obtained from Nissan Company. Each car has its unique 
PIN codes. Before obtaining the PIN, customer must firstly provide a 5-digits identification code(consisted of numbe rs and letters)written on BCM,  or read it from related BCM subsystem via Scan tool. 

After obtained PIN code, Scan tool can be used to initialize the ignition key by accessing NATS system and perform appropriate DTCs diagnosis or key replacement via 
re-programming operation. For details, please refer to steps below:   
1. Select "C/U INITIALIZATION" mode;   
2. Turn the ignition key to "ON" position;   
3. Input password (PIN code);   
4. Press "START" button to start the control unit initialization process; 
5. "INITIALIZATION COMPLETED" indicates t hat the initialization  of the IMMU and ECM 
is finished;   
If the fifth step shows "INITIALIZATION STOPPED, or FAILED", it indicates the 
initialization by decoder uncompleted or failed.   
6. Turn the ignition switch to "OFF" position and pull out the key.   
7. Turn the ignition switch to "OFF" or "ON" position;   
8. Read DTCs;   
9. Replace IMMU if displaying “IMMU”, and then use X-431 or CONSULT-II to perform C/U 
INTIALIZATION". 
Perform "C/U INTIALIZATION again if displaying “No DTCs”

2. Ignition key registration 

1. Insert the 1st key into ignition switch, and tu rn to "ON" position to remain for more than 5sec, and then turn the ignition key to "OFF"  position and pull out the ignition key;   
2. After 5sec, when the anti-theft indicator fl ashing, insert the 2nd key, and turn to "ON" position to remain for more than 5sec, and then turn  the ignition key to "OFF" position and pull out the ignition key;   
3. Repeat the above-mentioned steps which can match up to five keys;   
4. Open the door or start the engine to exit the key registration; 
5. Confirm each key (remote controller) can start the engine as the normal. 

If the remote control keys can start the  engine, pay attention to whether the remote 
controller can open and lock the door. Otherwise , the remote controller must be matched. 
There are two matching methods below: 

Method 1:   

1. Close all the doors(the operator shall be inside the car), and lock the driver's door  
2. Within 10 seconds, insert the ignition ke y and pull out, which shall be repeated for more than six times;   
3. Hazard warning lights will flash twice;   
4. Turn the ignition switch to ACC position;   
5. At this time, press any one button on the new remote controller once. (Hazard warning 
lights will flash twice);   
6. If copy another anti-theft remote controller, turn the "LOCK" button on driver’s side to "UNLOCK" and then to "LOCK", then repeat step 5;   
7. If matching is completed, just open the car door and pull out the ignition key.

Method 2:   

1. After opened the trunk, close and lock all the doors;   
2. Within 10 seconds, insert the ignition ke y and pull out, which shall be repeated for more than six times; 
3. Open the driver's door and then lock;   
4. At this time, press "LOCK" button onc e on new anti-theft remote controller;   
5. If copy another anti-theft remote control keys, to repeat the steps 2-4. 

Intelligent Key Registration: 

1. Before the registration of intelligent ke y, firstly register the ignition key.   
2. Turn the ignition key to ON position, register the intelligent key via REGIST I-KEY ID 
function of I-KEY system. During the registration, the intelligent key shall be inside the car. Besides, press any one button on intelligent key.

Notes: difference between intelligent key and remote control key. 
Remote control key: starts the engine by remote control the ignition key chip inside, 
therefore, after the ignition ke y registration, just insert the ignition key inside the remote control key can start the vehicle via remote controlling. Such as: TIIDA of 2007 and 2008. 
However, after such key matching is completed, the remote controller shall be matched for 
door opening and locking.   
Intelligent Key: such key has its own intelligent  chip inside, therefore, after the ignition key registration, the intelligent key also must be matched before starting the engine. Refer to Intelligent Key Registration for matching method. 

DTCs of NATS

The most common DTCs of NATS are P1610, P1611, P1612, P1614, and P1615, etc. 
Their relative meanings are as follows: 
[P1610]: LOCK MODE (dead lock mode);   
[P1611]: ID DISCORD, IMMU-ECM (the ID signals between IMMU and ECM are 
inconsistent, which  means the system shall be initialized);   
[P1612]: CHAIN OF ECM-IMMU (a fault on NATS communication line between ECM and 
IMMU);  
[P1614]: CHAIN OF IMMU-KEY (a fault on the line between IMMU and KEY which causes 
the BCM can’t receive the key ID signal);   
[P1615]: DIFFERENCE OF KEY (BCM has received  the ID signal of key and identified it 
as the illegal ） 
NATS will enter into dead lock mode if using  an unregistered or invalid key to start the 
engine for more than five times, at this time, even though the correct car key also can not normally start the engine. To unlock the mode,  the system shall be initialized again. If the detected DTCs are related to engine system, the related DTCs  will also display on ECM. 
Before clearing the DTCs memory on NATS, firstly check the DTCs on engine system 
because while deleting the self-diagnostic codes of NATS,  the memory on the "engine" 
self-diagnosis system  will also be cleared.

I got this post from http://www.x431.com.