you guys are too much
This is the plug which carries "accessory wires" connections for dash, meter, and other things from the ECU, it may also containt 12+V current containing wires going to the ECU. It is the plug you need to wire up to get the engine running as it should be. In an N16, you will find the female connector for it mounted on the dashboard or wall somewhere.
hope at least you understand what i am saying.