Follow the cable. It surely ain't wireless!
But as a rule of thumb, ideal location is as low and as centered as possible, so look under floor panels.
Or wait for someone who, unlike myself, knows the specific placement on a Sq55!
We couldnt find it , the wires lead to behind the helm and then to starboard we didnt want to dismantel the boat completely so disconnected, new one fitted, sea trial done and calobrated, all good.
Thanks for replies.