Kevin you are suppose to install the gray wire that goes to the lamp in the fuse panel 12v source. Look at the tach plug you will have 5 wires 1 brown for lights,1 black to light, 1 purple to tach, 1 black to the tach, 1 black to tach. is this correct?
I'll post the instructions for you next post.
they don't talk about the light wire in it and they refer to the tach plug, not the harness plug.