Hey guys, I'm currently swapping a VQ from a 2004 350z into my 03 g35 sedan . I've got the new motor in and it seems my security system is locked up. The motor turns but does not turn over, the security light next to the clock is solid red with the ignition turned to acc or on. When doing a complete swap of the motor is their something I'm missing that needs to be done related to the security system ? The car has been sitting for 4 years and last time I started it was about a year and a half ago where it ran with the original motor without any security issues . I've also already put a new battery in to see if that was the issue. Any clues would be appreciated, thanks .

 

From my search for this Immobilizer issue it was clear that their was no method of resetting this system besides taking your car to the dealership to reprogram it. The main indicator that their is an issue with the immobilizer is the security light on the dash will stay solid red when the ignition is turn to the on position. This prevents the motor from getting a spark and it also disables your fuel pump as it wont even turn on.

The solution I found was to disconnect the Ecu , turn the ignition to the on position then back off. After that I reconnected the ecu. This cleared the security light which then aloud the fuel pump to turn on and the engine fired. Manually trying to reset the ecu with the pedal method wouldn't work, I believe it was due to the lock up.


I was to the point of calling a tow truck to get the car to the dealership to have them reprogram it. I wasn't able to find any solid information on fixing this issue from any forums, so I hope this may help anyone else that ends up get this issue. It can be caused by something as minor as your key being to close to another infiniti key or something on your key chain.

 

As long as you're just swapping in a new motor and keeping the same ECU/BCM/harness/ Nissan programmed key you shouldn't have any issues with NATS (Nissan Anti Theft System), but you are correct that NATS was what was causing it to not start. Its an issue when you swap the motor into other chassis and have to disable it with an Uprev reflash, but you shouldn't have had any issues with it.

You may have had some stored NATS related codes that were preventing it from starting and disconnecting the ECU cleared them. Anyways glad you got it figured out.