FCV-585 to Garmin 527


New member
I need help connecting my FCV585 and Garmin 527 via NMEA 0183. I’m using Port 2 on the Garmin and Port A on the Furuno. This is what I have and I’m not getting any communication:

Furuno Garmin
White (TX-A) Violet (RX-Port 2)
Yellow(RX-A) Grey (TX-Port 2)
Green,Blue Ground

I've tried this connection with and without the Furuno blue wire. The Garmin GND and Furuno Green and blue are all connected to a common ground.

The Furuno is set to NMEA 0183 in/out and TLL out. Also, I tried all NMEA 0183 settings (version 1.5, 2.0, 3.0) The Garmin is set to NMEA 0183 on Port 2.

I’m testing this on the trailer so the transducer is not hooked up to the Furuno but I’m not getting position info in the NAV box on the Furuno.

Any ideas?

You might want to run the wiring by Garmin, but it appears to be correct.
Maybe another user has this Garmin and can provide you some guidance.
I would turn off TLL because Garmin doesn't support that sentence.
You might trying running the NMEA Port Monitor on the FCV585 and see what NMEA data is coming into the unit from the Garmin.
I'll try it with TLL off. I ran the port monitor and didn't see anything. I'll also run this by Garmin and post any useful info.

Garmin says my wiring is correct. I guess it's a setting then. I'll double check the grounds but they're all connected to a common ground where the power grounds are. The Garmin setting is simple: NMEA 0183 Port 2 and that's it. I will disable the TLL on the Furuno but can someone explain what NMEA version 1.5 - 3 means?
In looking at the Garmin wiring diagram, they use a common ground for their two output and two input ports. Garmin's ground is the same as the ground for the input voltage. The Furuno NMEA ports use a isolated current loop configuration which doesn't use a common ground. When you tie the Blue/Green wires to the black you risk taking out the 585's NMEA ports. If the 527 has a NMEA window you can try connecting only the white to the gray to see what happens but most likely you will need a level convertor.