Autopilot not working on nav or track mode

[jaba-who]

Had an interesting problem occur today.
My AP74 seems to not be getting GPS associated data from the D180. It previously worked well.
My D180 gets data from my garmin 296 which is displayed on the 1/3 page with HSI etc so I know the link from the GPS to the D180 seems to be OK. And the AP74 works on heading and altitude mode (although much less smoothly than before)

What seems to have stopped working is the GPS-D180-AP combination.

I had to do a reset of the GPS a month or so back but don't know if that was the trigger event.  

Can the GPS data be enough to run the HSI page but not the AP?

Any hints about what could be happening?

 

[sibinelli]

I have the same exactly problem, on the HSI I cam see the garmin 296 data, but the ap74 just does not engage NAV or TKR modes,

the data hate on the gps is set to normal

 

[dynonsupport]

If the EFIS doesn't think there's a valid waypoint for any reason, NAV won't work on either the AP74 or in the MAP menu. You do need to have an actual satellite lock, and a waypoint programed and active, for the waypoint to be considered valid. The data rate under the advanced NMEA setup on the Garmin device also needs to be set to normal, not fast, as you've mentioned.

 

[jaba-who]

Flying now, (the joys of an iPad)
AP74 will lock on with heading mode and track mode but doesn't light up or turn on on nav. The gps data is in as a route and the HSI page shows the right track and distance to the next waypoint so I can only assume it's getting all the info.

Jaba-who

 

[jaba-who]

Some further changes today.

I lost my GPS contact with the D180. No GPS data to to the HSI page as well as no winds data in the information block on the main screen.
Landed and checked the wiring joins. Nothing obvious but pulled them apart and reconnected them. Got the GPS data back to the HSI and winds info. But still no nav mode on the AP just heading, track and altitude.

The first question is - have I thought this through right?

Heading mode just uses the compass for it's working. But does track mode use anything from the gps?

 

[dynonsupport]

Hi,

Track mode follows a GPS based ground track, GPS nav mode requires a GPS NAV source with a CDI needle on the HSI. HDG mode requires only the compass.

 

[jaba-who]

OK
So this makes the problem even more difficult to nut out.

Tried multiple times over the last week with same result.  My AP is working on heading and track mode. Though it is hunting a bit more than before on both modes.

The Dynon 180 has a HSI on the HSI page with valid (magenta coloured) direction and distance and track information displayed and the arrows on the HSI all pointing in the right direction.

The D 180 is also giving me calculated wind speed and direction (which I think requires GPS as well)

So I can be certain that the GPS is talking in the right language to the Dynon 180.
When I go into the AP menu on the Dynon instead of the AP74 the only modes shown from which I can choose are track and heading.

I interpret this as the info break is happening between the GPS and the D180 not the D180 and the AP 74.  (Not sure this is a valid hypothesis but that's all I have at present.



So what could be going on so that the D180 gets info enough for track mode to work but the nav not?
Surely the same info is required for both, just that it gets used a bit differently.

Any more ideas?

 

[dynonsupport]

First, make sure your GPS is set to NORMAL mode in serial port setup. You mention a GPS reset which would mess this up for sure.

Distance and course on the HSI is not enough. Do you have an actual CDI needle on the HSI while you have a waypoint in the GPS? I can't tell if you have that or not from your descriptions.

 

[jaba-who]

I'll recheck the output setup and take a screen shot so we are all sure of what is there. I hardly ever use the HSI page so I am not sure of what should be there.

 

[jaba-who]

Finally got a chance to look at the Garmin 296 settings and it's fixed.

The settings were set for NMEA in/out
Rate Normal

Found a menu for Advanced settings - went into that
Cant recall what it said but didn't change anything.
Just backed out of that.

Changed all settings to none. Lost all the info to the HSI page - just a box with a compass rose like circle but nothing else.

Then re-ticked NMEA In/Out
Rate normal

and viola! All the info came back including the magenta arrow on the HSI rose.

Tried the NAV mode and it works.

So basically I did nothing. Just turned off the settings and then reinserted them.

Somehow it must have just needed resetting.