How to Use the Extra Wires on the Power Cable of a Garmin Fishfinder

Not all of the wires in the harness are required for use. To connect the unit to the power source, only the black & red wires are required (black to ground, red to positive). Here are descriptions of the other wires in the harness:

• The Blue wire is used for a NMEA data out connection to another NMEA compatible device. The fish finder outputs NMEA 0183 version 3.01. The receiving device must be compatible with this format and looking for the NMEA sentences DPT, DBT, MTM, or VHW.
• The Brown wire is used for a NMEA data in connection to receive data from another NMEA compatible device.
• The Yellow wire is used to connect to an external buzzer or alarm to alert you to any alarms which have been set to sound on the device. The Yellow GARMIN wire connects to the negative end of the external alarm. The positive return on the alarm will connect to the red positive wire of GARMIN.
• The green, white, and any other colors present have no connection purpose related to your fishfinder. The 18 Pin connector wiring harness is used by several other devices which utilize these wires.

If the device is only being connected to power & do not require a NMEA interface, PC connection, or external alarm support, only the red & black wires are required.