GPS networked to autopilot

[NCountry]

I"ve searched the forum backwards and forward and just haven't hit on the information I'm looking for. I'm sure that what ever I'm doing wrong is incredibly simple but just can't quite hit the right solution.
Here's the problem......
I've networked my nmea 0183 compatible lowrance M68C to my ST4000 autopilot and my DSC radio. The M68C is sending information and both the radio and autopilot are receving it. I set a course and press navigate to way point on the M68C with the autopilot turned on then I press the keys for the autopilot to follow the course sent by the autopilot. ALL the alarms go off on both the autopilot and the M68C. The display on the ST4000 starts switching between flashing "stbrd" and "port". It does not follow the gps to the way point or navigate the course entered. Am I just pushing the buttons on each unit in the wrong order? I've checked the the owners manual for all and the information is VERY limited but the command codes do match up.
I've tried different combinations of activating the autopilot and the GPS but don't seem to have hit the right sequence. Any suggestions? I know this has got to be simple.

[artbyjody]

Are you locking the wheel before engaging the auto-pilot?

Wheel under auto-pilot should be locked, and you should hear / feel the wheel turning according to direction. If not locked then the autopilot keeps reversing itself but the wheel never moves because it is not engaged...hence the flashing - port and starboard...

[NCountry]

I tried it both ways. Same result...

[artbyjody]

Without even considering that GPS nav...


Can you engage the clutch for the Autohelm - and use the keypad to steer the boat with the + - keys? Because if you can not do that then you'll need to start checking connections to your control head and other parts of the Autohelm system...

[NCountry]

The autopilot is fully functional and works fine as a stand alone. It also works with the GPS connected until I set the track control on the autopilot and try to navigate to a point using it and the gps.

[sailingdog]

Ncountry-

Was the ST4000 ever working as a standalone autopilot? If not, the problem may be the autopilot itself.

If the ST4000 did work initially, did you try using it as a normal autopilot after connecting the GPS to it? If so, does it work that way?

If not, then the problem is probably either a wiring issue, which I think is unlikely since the GPS information is showing up on the GPS and the DSC-equipped VHF--or it is an autopilot configuration issue.

Have you checked to see if your autopilot has the latest firmware update for it?? Have you put the autopilot into "GPS route" mode??

[JiffyLube]

If the GPS is wired through the plotter to the DSC-VHF radio, and the radio is working in DSC, then we know that the plotter preferences are 'nmea in and nmea out'. Does the autopilot software have a preference setting?

[NCountry]

The autopilot works as a stand alone. Still does after being wired into the GPS. I can navigate with the autopilot using the + and - buttons. Other than a short set up after connecting the GPS there are no preference settings for the autopilot. The alarms all start going off when I press the autopilot to go into "track" mode which I assume is the same as the GPS route mode. The owners manual used the term "Track Mode" when discussing connecting the GPS to the autopilot. There is no mention of a GPS route mode in the manual.
I have noticed that the autopilot actually seems to hold a course better now that it is connected to the GPS, at least until I try to enter the "track"mode.
I'm wondering if the "port" "strbd" flashing on the LCD display on the autopilot is some sort of error code but there's no mention of anything like that in the owners manual. (Believe it or not I actually read the directions! VERY unusual for me.

[brak]

Autopilot will be using speed information from the GPS to better control the boat, so thats the improvement in tracking.

How do you set up the course on the GPS? I would suggest instead of doing full routing, setting a single waypoint in the general direction of where you are already going, and trying to go to that waypoint first. See if autopilot would like that more.
Also, check that NMEA messages GPS puts out are compatible with what autopilot expects. Usually you have no control over what autopilot will accept, but GPS may have a selector saying which messages will be output - autopilot may use XTE or bearing to waypoint or whatever.

[sailingdog]

Track mode is GPS mode.... Different manufacturers call it different things.