Garmin GMR 190-00669-02 - Manual (Page 8)

6 GMR 404/406 Marine Radar Installation Instructions
Step 
Connecting the scanner
Connect the scanner power cable (Red and Black) to Voltage Converter output cable (Red and Black) using the supplied heat-shrink crimp
connectors. DO NOT cut the scanner cable and DO NOT remove the in-line fuse located on the scanner power cable. After crimping the
connections, heat the connectors to shrink the housing for a water resistant fit.
Connect the scanner to the vessel’s water ground using an 8 gauge copper cable. The scanner connection should be made on one of the four
mounting studs using a M10 nut and flat washer to secure the cable.
Wiring Diagram