S-1000 terminology

[Captrichie]

"connect the S1000's -ve in (NMEA 0183 IN-) lead to the Ground (Power & NMEA 0183) lead of the Garmin 741XS power/data harness"

assuming ( see below) that means connect the GPS messages back TO the S1000 to ground on the same negative panel as the GPS multi purpose ( black ) Ground . As you know , the -ve out ( blue ) if I use the orange +ve in for incoming course data from the GPS (blue color). orange to blue and blue to black (ground).


I made the above connections, went to set-up and within 2 seconds the signal was good so I did the setup test: The pump powers up when press starboard arrows and away it goes. The port, however, is unresponsive . As if polarity to the pump does not reverse.
In your experience what should I check first? Thanks in advance!
Rich