Garmin 430 Lost GPS signal Nav Issue

2001 Cirrus SR-22 Dual Garmin 430 non waas. Sandel SN 3308 HSI, S-Tec 55 Autopilot.

Has anyone ever had this happen. Intermittently Nav1 will have complete loss of GPS signal. Nav2 has no issues during the same timeframe. Not transmitting, fuel pump, flaps or anything like that. Signal levels come and go randomly, sometimes for only a few seconds, sometimes for several minutes. Had this issue very intermittently last year, and then everything was fine until a few weeks ago.

Has anyone had this happen? And what did they have to do/replace to get it fixed?


Linky to video of described behavior

I am recently troubleshooting similar behavior. Check satellite signal strength while changing pages on MFD. Some kind of interference. Mostly on map page. I switched NAV 1 and 2 antennas and need to insure separation of cable bundles to see if I can clear it.

I have a PA28R with a Garmin 430 and have experienced intermittent loss of GPS signal situations.

Yesterday, it seemed the 430 was actually jamming my stratus (and that of a pilot friend - we were shooting approaches) . Both stratus and the 430 had not GPS (which provided good practice to fly approaches the old fashioned way). When I turned off the 430, the stratus came back to life. When I turned it on, the GPS annunciator light of the stratus went immediately to yellow.

Today everything worked fine. GPA and stratus came up immediatley and had GPS reception in a few seconds. Any idea what’s going on?

If it is a 430W I suspect your GPS antenna is failing. If it fails in a certain way it puts out a significant amount of interference and it can knock out all GPS equipment on board. I have had it happen and I know one other pilot that did. Once the antenna was replaced the problem stopped. I have a great video somewhere of all GPS signals being lost when the offending 430W was turned on.

This is a common problem. 430 NON WAAS antenna is located under the glare shield… Its held in place by Velcro believe it or not. It has probably fallen off, which will happen alot. Can fix it your self. Just take the glare shield off and re-attach. I have always just taken out the MFD and and did it, but in another thread people said not to do that… oops lol

No bid deal, just get some new velcro

While you are right that it is a common answer for many vintage Cirri it would not likely be for GPS 1 in that vintage. The number 1 antenna in an early plane like that was in a cavity in the roof. Number 2 was velcroed under the glareshield but not number 1. I always thought that was a great location for the antenna, just below the fuselage skin above the headliner between the CAPS handle and the windscreen.

Todd, I know this is a relatively old post, but do you recall the outcome? I’m experiencing similar issues on an aircraft of similar vintage

Not Todd, and this just echos my earlier post, but with your serial number i would assume both of yours are mounted under the glareshield. It really is EASY to remove the glare shield and check yourself. Just 2 screws on each side then lift up. There is 1 wire connecting the LED lights, just simply unplug that if you need to take it completely off, but you shouldnt need to. My bet is you open it and see the antenna has fallen off. Had the same issue in serial number 0350 probably 8 times in 5 years. easy fix.

Thanks Billy, I’ll check that out. My G1 SR20 started loosing GPS signal on #1 out of the blue (non-waas). I do know that I have a large GPS antenna up top between the doors, which I assumed was #1’s antenna. I’ll check below the glare shield today or tomorrow and let you know what I find!

Up top on the outside? Thats your Xm weather antenna, not GPS.

Oh, thanks! Learn something new every day!

Or if you have Skywatch the antenna for that is a large antenna between the doors. The GPS antennas on top if present are just behind the windshield (#1) and much further back (#2.) GPS2 may be a combined GPS/XM antenna.

See here:

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Samsung SM-T820

Thanks for the photo Clyde. Based upon that information, I believe I do not have external antennas for either GPS.

Well, not so fast. That com antenna is a blade style, different than came from the factory. Some blade antennas are combined COM/GPS. Maybe, maybe not. Give that thing a closer look.

More likely the COM antenna is combined with XM. The shape is the same as the COM/GPS antenna, but AFAIK combined COM/GPS antennas were never fitted at the factory whereas COM/XM antennas were.

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Samsung SM-T820


True from the factory. I was thinking something that might have been installed after that. Either is possible, you never know. I don’t know the history of the plane.

If XM was not factory, I’m not aware of it and I don’t see it notated as being added with a quick review of the logs. I’m reviewing a scanned copy of my logs, so I may not quite see something in them that I would in the paper version, but I am 95% sure it’s factory. I’ll check and send more detailed photos when I get back out to the airport.

while youre at the airport, it really is nothing to take that glare shield off and you will see if it has the antennas under it

Can’t you just undo the MFD and see the same area?

By way of follow up, I removed my glare shield last night and discovered that I only have one GPS antenna under there, which was attached well. I also did some research on my COM 1 antenna, a Comant which is apparently a combined GPS and COM antenna (did not know that when we started this adventure). I went ahead and removed both GPSs and sprayed some Deoxit on all connections except the base of COM 1/GPS 1 antenna, since it’s above the headliner. I pulled it out to the open sky and signal strengths on GPS 1 were strong, in fact a bit stronger than GPS 2.

I did not have time to fly and this is an intermittent problem, so I’m not sure it’s solved. Will post back future findings for posterity’s sake.