multi function tack light

I have the Yamaha multi function digital tach for my 1995 130hp.
The tach works fine but the backlight does not go on. There also is red lead on the harness that does not seem to have a home. Any suggestions?

[boats.net]

The red lead is for the speedometer. The backlights are the blue wire, connect the blue to yellow if want light to come on when turn ignition key on, connect blue wire to navigation light switch in boat if want to work with boat nav lights, DO NOT connect to both key and nav lights.

tach light

I did just what you said....thanks, that was the problem. Great help.