Shouldn't make any electrical
connection differences, though. According to your drawing, the Garmin
uses the older RS232
NMEA and the B&G the newer RS422 NMEA. Should be able to make it work
by connecting the black ground wire of the Garmin to the blue signal- wire of the B&G, blue signal wire of the Garmin to the red signal+ wire of the B&G, How does the 3 pin cable connect securely to the 2 pin socket?