GPSMAP® 740s | Garmin GPSMAP 740s is a stand-alone touchscreen chartplotter that brings a new level of functionality to your vessel. Featuring a brilliant 7" (17 cm) display, GPSMAP 740s puts all the information you need right at your fingertips. GPSMAP 740s is preloaded with U.S. coastal maps.Manuals · BlueChart g2 Vision Connecting the Wiring Harness to Power - garmin Route the wiring harness to the power source and to the device. Connect the red wire to the positive (+) battery terminal, and connect the black wire to the negative (-) battery terminal. If necessary, install the locking ring and O-ring on the end of the wiring harness.