friedEGs

Okay, I have a 90 ex civic, (like an si) with a y8 head and block. The intake manifold, dist, and ecu are all stock from the 90 civic. Now, the power to the light is simple, and the dist wire for the rpm signal is ready. Now there is a positive lead to teh light which I am assuming I would wire to the 1 wire at the solenoid. My ? is, how does the system ground back to the shift light? Doesn't the head automatically ground the signal wire? Won't that keep the vtec on all the time?