Hey everybody I read alot about anything close to my situation but haven't really found anyone with the exact problem. I'm having this problem on my 2000 Nissan maxima se automatic I'm getting the solid red security light next to the clock so I thought I just needed my keys reprogrammed so I called a local locksmith and he said he does maximas a lot but when he tries to connect his tool to my cars computer it wouldnt connect it kept saying communication failed so I'm not getting power to my computer or its fried I checked every fuse I could visually and with a multimeter but couldn't find any blown. Next I took out the ecu opened it and looks perfectly fine. Previous to all this I changed my upper manifold gasket everything was good but somehow my battery positive wire fuse got blown so connected the alternator and starter wire to the positive battery poll just to hear how she ran (stupid I know!) But everything was good startes right up running good Then i realized I forgot to install the injector clips. So took everything off again and put back together now I'm getting the red security light on solid and can't communicate with ecu and no yellow engine light comes on before cranking. Can anyone tell me the location of the fuses or relays connected to the ecu ? Thanks

 

Sorry to bring this thread from the dead, but I am having the same issue on an 01 Maxima with Auto trans. Solid security light cannot connect to ecu with either my elm bluetooth code reader or my Data Scan II cable. I sent the ecu in to get repaired thinking that was the problem, but the tech said he was able to communicate with it fine. I have another ecu in the car currently and can communicate with that one using both my scanners. Did you ever get your issue solved? Was it a NATS problem? Thanks in advance,

 

Yes, the solid security light during starting indicates a NATS problem. Your car does not recognize the key you are trying to start with. If you attempt to start too may times, your car may get into a state called "NATS lockout".
This forum has plenty of information on this subject, just search a bit.

 

That doesn't explain not being able to communicate with the ECU, unless I am missing something? How can I get it out of lockout mode if I can't even communicate with the ECU?

 

I am not saying that your car is in NATS lockout mode - I don't know one way or other. I am just flagging the fact that NATS lockout is a possibility. Should your car indeed be in that mode, then the procedure for escaping it is described on page EL-338, paragraph #2, of the FSM.

Now re. your inability to communicate with one of the two ECUs: Since you can communicate with one of them, then the problem is not with your fuses or other common parts. It's something specific to the "bad" ECU - either it has been physically damaged, or its connector pins are bent or not properly seated, or something like that.

 

One more thing: NATS lockout is entered when you try to start consecutively five or more times, under the following conditions:

• With an unregistered ignition key,
• When your IMMU, or ECM, or both is/are malfunctioning.

Based on what you told us, I wouldn't be surprised if the above happened. So I would try the escape procedure:

1. Turn ignition switch OFF.
2. Turn ignition switch ON with registered key. (But do not start the engine.) Wait 5 seconds.
3. Return the key to OFF position.
4. Repeat steps 2 and 3 twice (total of three cycles).
5. Start the engine.

It should only take a couple of minutes.

 

So I have a very similar problem in my 2002 that I'm chasing right now. When your key is in the on position (with security light on) is your MIL on?

 

Would say you have
to establish a closed circuit between the data link and ECU connector. Then a closed circuit within the ECU data link circuit to main power-in pin. you should get a closed circuit.
After establishing that you should be able to connect right?