Garmin 5212 doesn't recognize GPS data over NMEA2000

[tkaustin]

I wanted to add AIS reception to my 2010 RT-25SC, so bought a Standard Horizon VHF Transceiver (GX2410GPS). That communicates on NMEA2000, so I disconnected the NMEA0183 from the Garmin 5212 MFD. Even though the new radio reports several GPS satellites over NMEA2000 on the Garmin Skyview screen (see pic), when navigating it has no idea where we are.
Extensive search for some setting on the 5212 to use NMEA2000 GPS data for nav found nothing.
Does anyone know why the 5212 can't navigate using NMEA2000?

File attach link says file is too big. Here's a link to my cloud copy.

New photo · Monday, Sep 15, 2025

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In case that doesn't work, the picture is the Garmin Skyview screen showing 8 GPS satellites found.

 

[Full_O_Fish]

First thing to check would be the software version of your 5212. Newest available and most stable/compatible version is 7.8

Early software versions were known to have some nmea2000 stability/communication issues.

Beyond that, check the nmea2000 device list on the 5212 and verify that the VHF is showing correctly. Then verify that the network has the correct number of terminators (2) and no excessively long drop cables (<~18'). If that's all good, then go into the "preferred sources" list and select the VHF instead of auto or any other listed source.

Lastly, both nmea0183 and nmea2000 can be connected and utilized at the same time, so just reconnect your old GPS and manually select it from the preferred source list that way GPS comes from 0183 and AIS comes from 2000

 

[Jesperjo]

Is it the radio/AIS transceiver that doesn’t have a GPS fix, or is it the Garmin 5212? You said “even though the new radio reports several GPS satellites over NMEA 20900 on the Garmin Skyview screen, when navigating it has no idea where we are.” Does “it” there refer to the Garmin, or the radio/transceiver? Presumably you have a GPS antenna connected to the Garmin, right, and it has worked in the past? If it is the Radio that doesn’t have a GPS fix, is it configured to get GPS data from the NMEA 2000 network or is it configured to use its own internal GPS antenna?