ST60 Wind - Suspect wire damage

I have reason to suspect wire damage in the mast. However I am confused by the readings I get:
Instrument powers up displays --- and straight up arrow.
When all wires are connected I have 8V across all 4 wires from GND
(does this indicate continuity to the masthead and back?)
When only GND and Red connected, I have 8V from
GND to Red and also 8V on the return line from the masthead on Blue Green Yellow.
So I am confused as to what I'm seeing or, coincidentally with the extreme street on the wires did the transducer fail.?
Anyway, thanks for any input!
Michael