5thgencivic

I just finished installing a greddy kit on a friends car(sold my kit to him) He has a 95 4 door with a z6. I noticed he was missing one of the wires for the blue box hookup. The wire that the gray blue box wire hooks up to(INJ G) was missing. My car had the wire. The box light blinks and the car runs fine. Anyone know what the gray wire is for on the blue box? Thanks.

Nate