Hook up the grey wire to the positive terminal on the speaker and your amp or receiver.
What color speaker wires are positive and negative?
Colour-coding: Speaker wires are often colour-coded, which will help you remember which one is positive and which one is negative. The most common colour coding is red and black, where red is positive and black is negative.
Is GREY or black positive?
Recognize that the black wire is the positive one, the white wire is the negative one, and the green wire is the ground.
Is the blue wire positive or negative?
Yellow is positive, blue is negative.
How do I identify speaker wires?
0:082:10TVS Pro Quick Tip: Identifying Speaker Wires - YouTubeYouTube