stevetfiidalgo
Member
- Joined
- Mar 14, 2023
- Messages
- 7
- Fluid Motion Model
- R-31 CB
- Vessel Name
- Scout
I had some interesting problems with my autopilot on my 2016 RT31S that I thought I'd share in case there are helpful to others in the future who might be experiencing intermittent problems with the autopilot or Fusion systems.
See below for tips on Fusion stereo and N2K wiring, and how to put your autopilot into "Dealer" mode for calibration.
There was a collection of symptoms that I was experiencing:
I have a "GHP Reactor Hydraulic" autopilot system (with newer CCU, not the "ball" one). My stereo is the older Fusion 750
The usual answer to the autopilot course problem to check for proximity of the course unit ("CCU") to magnetic interference - maybe too close to an electrical appliance such as the refrigerator? On my boat, it was located behind the middle set of drawers in the galley, and seemed far enough away from interference, especially the refrigerator.
One problem was a broken "T" connector from the CCU, causing intermittent problems. I replaced the T's with solid backbones (based on other posts here) and extended the cable to the heading unit to avoid strain. This seemed to reduce the frequency of problems - now it would sometimes work for a while!
I also got a *lot* of amazing help from Garmin tech support and we did some recalibration of the autopilot compass. That fixed the course accuracy issues. FYI, you can do more in-depth calibration by putting the autopilot in "Dealer Mode". From the autopilot control, navigate to "Menu/Setup/System/System Information", then press and hold the center-button for 5 seconds. (Press and hold the right-button for 5 seconds goes to diagnostics).
I still hadn't figured out the source of the power supply to the NMEA Bus, which was at least powering the autopilot control unit, and the Fusion wired remote. Some checking of the wiring showed an interesting arrangement to power the N2K bus.
Both the Fusion stereo main unit and the remote head are connected to the N2K bus - that's how the remote unit communicates to the main unit. There is a feature of the Fusion called the "NRX Power Option" that allows you to connect the remote unit directly to the stereo in a simple N2K network powered by the stereo. On my boat this feature was used to power the entire N2K network via the stereo.. This is expressly warned against in the fusion manual!
Also, the network backbone was not properly terminated on both ends.
As an aside, this link from Actisense The 3 easiest ways to diagnose NMEA network issues gives some more details on testing N2K network terminations and power connections. I bought a short drop cable and cut off the ends and stripped the wires to make two pigtail connectors for testing.
I fixed the problem by moving the Fusion (and its remote) to its own separate network, and adding a power tap to the intended fuse for the main network. All of the intermittent communication problems have been resolved. As a bonus, the Fusion and remote no longer freezes up from time-to-time. "Sweeeeeet"
It is also possible to disable the "NRX Power Option" in the fusion settings, and keep everything on a single N2K network (wired to a separate power source), but I personally don't see any value in the stereo/chartplotter display. I would rather that a failed stereo not be able to take out my autopilot!
See below for tips on Fusion stereo and N2K wiring, and how to put your autopilot into "Dealer" mode for calibration.
There was a collection of symptoms that I was experiencing:
- Autopilot course was off, and erratic
- The autopilot would stop working with the GPS on an intermittent basis. Specifically, it would not follow an autoguidance route.
- The Fusion stereo (main unit) and wired remote unit would sometimes freeze up and I had to remove their fuse to reset
- The source of power to the NMEA 2k bus was a mystery. I could measure power on the bus, but the fuse clearly marked for the network had no connections
I have a "GHP Reactor Hydraulic" autopilot system (with newer CCU, not the "ball" one). My stereo is the older Fusion 750
The usual answer to the autopilot course problem to check for proximity of the course unit ("CCU") to magnetic interference - maybe too close to an electrical appliance such as the refrigerator? On my boat, it was located behind the middle set of drawers in the galley, and seemed far enough away from interference, especially the refrigerator.
One problem was a broken "T" connector from the CCU, causing intermittent problems. I replaced the T's with solid backbones (based on other posts here) and extended the cable to the heading unit to avoid strain. This seemed to reduce the frequency of problems - now it would sometimes work for a while!
I also got a *lot* of amazing help from Garmin tech support and we did some recalibration of the autopilot compass. That fixed the course accuracy issues. FYI, you can do more in-depth calibration by putting the autopilot in "Dealer Mode". From the autopilot control, navigate to "Menu/Setup/System/System Information", then press and hold the center-button for 5 seconds. (Press and hold the right-button for 5 seconds goes to diagnostics).
I still hadn't figured out the source of the power supply to the NMEA Bus, which was at least powering the autopilot control unit, and the Fusion wired remote. Some checking of the wiring showed an interesting arrangement to power the N2K bus.
Both the Fusion stereo main unit and the remote head are connected to the N2K bus - that's how the remote unit communicates to the main unit. There is a feature of the Fusion called the "NRX Power Option" that allows you to connect the remote unit directly to the stereo in a simple N2K network powered by the stereo. On my boat this feature was used to power the entire N2K network via the stereo.. This is expressly warned against in the fusion manual!
Also, the network backbone was not properly terminated on both ends.
As an aside, this link from Actisense The 3 easiest ways to diagnose NMEA network issues gives some more details on testing N2K network terminations and power connections. I bought a short drop cable and cut off the ends and stripped the wires to make two pigtail connectors for testing.
I fixed the problem by moving the Fusion (and its remote) to its own separate network, and adding a power tap to the intended fuse for the main network. All of the intermittent communication problems have been resolved. As a bonus, the Fusion and remote no longer freezes up from time-to-time. "Sweeeeeet"
It is also possible to disable the "NRX Power Option" in the fusion settings, and keep everything on a single N2K network (wired to a separate power source), but I personally don't see any value in the stereo/chartplotter display. I would rather that a failed stereo not be able to take out my autopilot!
