Here is a copy paste from the Raymarine
tech support forum. I intepret this to be the blue 0-5 referenced to shield is windspeed. I'd check at the mast foot joint (if you have one) and the instrument plug
masthead cable check with a volt meter, on these colors, using the shield or bare wire as a reference point, to the red 8vdc should be there, then to the yellow and green you should see about 2-6vdc, and then to the blue 0-5 vdc depending on how fast the wind is blowing,. 8vdc going up and the rest coming back down, if nothing is coming down then the masthead transducer or cable is bad, if current
coming down then the display would be the problem.