Long story short i bought a water flooded g37 coupe and a crashed g37. I sucessfully swpped engine, Transmission, wiring, dash and all. But i only have one issue with this plug which i dont know what its for. One comes from behind the firewall on the drivers side. Its been a hell of a project and im almost done.

 

sometimes plugs are just there not connected to anything ie for features the car didnt come with. i think ive see that on my car too

 

that's for the flux capacitor feature.

 

the previous wiring harness had that connected. But the plug on this one is different.

 

it cant be. The flux capacitor is already connected and it was working good 😂😂

 

I think that connector is for extra accessories installed by the dealer, like illuminated illuminated kick plates, vehicle tracking system, etc...
The illuminated kick plates and OEM tracking system on my G37's are powered from such connector.

 

That small one looks like a two-lead plug, usually power for some kind of optional accessory. As stated before, sometimes there are loose unconnected plugs just hanging out, especially under the driver side.

 

That small connector is used to provide power and ground for the illuminated kick plates. It switches on/off with the door switch. It appears to have been added late in the 2014 model year production. Prior to that, power and ground to the kick plates was provided via a T harness on the BCM. (Source, just installed a set in a later build 2014 coupe)