Bill 3

The speedo (Livorsi) goes through its start up procedure, but lands on the 9 o'clock position (30 mph approx) which I have been told means it has lost communication with the antenna. I have a Garmin GPSMAP 741xs and have hooked up the NMEA output (blue wire) to my gps speedo. The speedo seems to see a signal of some sort depending on which output options I ask the 741 to output but I cannot get it right. The speedo either reads 0 and stays there or it reads about 5mph. If I send standard speed it jumps back and forth from 0 to 5. High speed output makes it steady, but will not show speed.

Anyway, can anyone tell me what settings I need to set to get this to work, or am I stuck buying a new antenna that will work?

Double Rigged

NMEA requires two wires. You mention hooking up the blue. You need also need a gnd which is the black (-) of the garmin. Make sure you are using NMEA 0183 out of the garmin and the blue wire is tx +. Black neg is TX-
This would go the GPS speedo NMEA input + using blue and - using black.
I assume the livorsi accepts nmea 0183.
Lastly make sure SOG sentence is turned on in the GPS. I think the sentence is VTG.
Hope this helps.

Bill 3

Thank you for the response. The previous antenna (Garmin GPS36) only had one wire hooked up, but used the same power and ground leads. The back of the speedometer only has on wire that goes to the sensor input plug. I am not trying to argue.

I read where the speedo will only accept 4800 baud and or one update per second. I don't think the Garmin 741 will send the info that slow no matter what settings I try.

I basically gave up and purchased a Garmin 18x and according to the wiring diagram, I am to use the same power and ground and one sensor wire. Hooked it up and works great.

Thank you again. Maybe this info will help someone else. For less than $70 shipped, it was the cheapest route I found to repair the speedometer.