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496 to Trutrak Pictorial Pilot Problem

N

N999BT

Well Known Member
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I have a Trutrak Pictorial Pilot and a Garmin GPSMAP 496 installed in my airplane. The 496 just replaced an aging GPSMAP 195 that had some intermittent issues starting to happen. The 195 was flawless in communicating witht the Trutrak, but the 496 seems to intermittently and and randomly break communication with the autopilot.

Has anyone else had this experience, and what is the solution?
 
Does this problem only happen when you adjust the GPS? If so, it's a known bug in the combination of the GPSMapxxx with the TruTrak autopilots.

When the GPS is busy (redrawing, zooming, etc) it shuts down the coordinate update on the serial link. The autopilot thinks that it's lost GPS data and reverts to magnetic track mode.

I've heard that TruTrak can fix this problem with a hardware update. If this is the problem you are having, you can also have a checklist:

"After any manual GPS operation, check that the autopilot is still in Nav mode."

Vern Little
 
I have that same problem with the 496/Pictorial Pilot. I sent my PP to TruTrak for the "update" but it didn't do diddly. Still working with Garmin and TruTrak to try to resolve this.
 
New Garmin Software Update

I went to Garmin's site today and noticed that there is a new software version as of September 25. I went to download it and one of the changes is they say they have fixed the intermittent dropping of the NMEA out. If this is true it should solve my problem. I will try it out and let everyone know what my experience is.
 
Another Update

I called Trutrak and Garmin again after the new software download. The problem is a little better, but when the communication between the autopilot and the GPS is interupted 4 times in a 20 minute flight IT'S NOT Working for me.

Garmin had me go to the advanced tab in the setup area (access by hitting menu). They wanted me to set it at NMEA in/NMEA out, normal rate (not fast), and turn off the Garmin proprietary stuff. I tried several configurations, but the problem is not fixed. They (the Garmin tech support guy) talked with his supervisor and claimed they had never heard of this problem.

When you lay down $2,800 for a GPS you would expect it to work at least as well as the 195 I had in there originally, wouldn't you?
 
Communications Problems

Howdy,

Is it possible that you have some noise on your communication wiring. The type of connection they use is very prone to noise and this may be a factor. Make sure your connections are good and that you are using shielded cable with the shield covering as much of the wires as possible on the ends and also only ground the shield on one end of the cable. Make sure it is not grounded on both ends. Make sure it is not routed near any noise sources. Also any loops in the cable will make like a really good antenna for noise so make sure there are no loops. Any distance of parallell runs of the cable with other wires expecially power wires might induce noice as well.
I wish these things used 4 wire differential inputs, then noise problems would be less of a problem.
 
It's not noise that's "causing" the issue. It happens (in my case) when the 496's screen refreshes.
 
I've got the same problem on my '296.

I don't think Garmin will fix it, if my experience with them is indicative of the quality of technical support that you can expect.

TruTrak is much more responsive, but they can't design a work-around unless they know exactly what Garmin is feeding them (hopelfully not the same stuff they are feeding us!).

My 'workaround' is to always check the autopilot if I've done any manual operations on the GPS. Sometimes, when zooming, the redraws can take a long time, and the serial link will shut down. This kicks the autopilot into magnetic heading mode.

From experience, I know the vansairforce forums (and other forums) have a lot of impact on vendors. With enough complaining, manufacturers take notice.

V
 
I don't know who you guys are talking to at Garmin, but I can tell you that their engineers are working fervently to resolve this.
 
Brantel said:
Howdy,

Is it possible that you have some noise on your communication wiring. The type of connection they use is very prone to noise and this may be a factor. Make sure your connections are good and that you are using shielded cable with the shield covering as much of the wires as possible on the ends and also only ground the shield on one end of the cable. Make sure it is not grounded on both ends. Make sure it is not routed near any noise sources. Also any loops in the cable will make like a really good antenna for noise so make sure there are no loops. Any distance of parallell runs of the cable with other wires expecially power wires might induce noice as well.
I wish these things used 4 wire differential inputs, then noise problems would be less of a problem.
Click to expand...

I put everything more or less in the same spot as my 195 which had no problems. I even used the same wire from the autopilot, just cut it and crimped on a new connecter. I think Dan is right, there is a problem with redraws or something that causes it to forget to send data to the autopilot, and then the autopilot goes into heading mode. VERY annoying.
 
Another Update

I recieved a reply from Garmin via email that said I should put it in Fast mode instead of Normal on the advanced page setup. I flew for about 45 minutes with the A/P in nav mode coupled with the GPS. It seemed to work much better, but still dropped the connection once. However, the heading indication on the A/P head never was lost. This is a vast improvement with this latest firmware revision.
 
FIXED

ok,
I had the same problem with a 396 and 496. The latest garmin update fixed my problem. You MAY have to also get you autopilot updated.

Jason Sneed
 
Another Update

I went on a short cross country flight yesterday. The 496 and the Trutrak worked flawlessly. I am very happy with Garmin for getting this issue fixed. I had the GPS on autozoom, so it redrew the map regularly, and it never broke the connection with the autopilot. Cool.
 
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