Wiring question on 48SPL remote control

[theonlyrobertson]

After someone butchered up my family's pontoon boat trying to fit an old mercury where a johnson 48 SPL resided, I have finally got the 48SPL running and pumping water. However, I have a wiring dilemma. On the remote control, just below the ignition switch there's a harness with three wires coming out of it. One is red (hot?), one is black (ground?) but the third one is blue. Can anyone tell me where this is used?

Thanks,

Dale