I have been sitting here trying to get a lock with my GPS while outside for about 10 mins.  No luck.  I generally get a lock between 30-60s when outside.  My GPS has worked fine previously.

Other than the CLI test (which only works if I have lock anyway), is there a way to check GPS function?

If my GPS unit turns out to be no longer functioning, what options do I have with the APM2?  Since my GPS is soldered directly to the board, is it possible to get another and use an extension?  I don't trust my soldering abilities enough to remove and replace the current unit


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It can take 12+ minutes to download the almanac data from satellites into the GPS the first time out of the box.  Give it more time.

I have exactly the same problem, how did it turn out for you?? 

Problem persists, i get satcount = 0, hdop=9999 and gps=1 from telemetry

Can we have an official answer about using an external gps? i don't mind if my onboard module  doesent work, if i can do my job with my old APM1 module. 


Is there an other process, beside :

-waiting for lock for an hour or so, 

- reset board (warm start)

- test CLI readings

-test telemetry readings

-check for unsolder traces

- fresh batteries

-clear sky 

To check the health of the onboard module??


The only think i've read to forum is cutting the TX trace, but not from an dev member or 3dr member. And without a photo.

I placed an issue 624 to inform dev team 




I also had the problem today. I have an APM 2 V2.4.1 and a UDB4 both using Media TEK GPS units. I was not getting a 3D fix with the APM 2 so I swapped out the GPS with no fix, then the GPS cable with no fix, then checked the GPS on the UDB 4 and it got a 3D fix within about 80 seconds. Switched the unit I had connected to the APM 2 still no lock. Installed the pre-compiled ArduPlane V 2.33 binary and got lock on the APM 2 in about 3 minutes. Downloaded my edited and compiled binary and repeated the test and got lock again .. so thought problem is solved. I then reconnected my lipo, ESC and board into the plane and then could not get a 3D fix again. One thing though it was very hot (around 40 degC) and the Media TEK GPS units were hot to the touch. I wonder if its not a temperature related issue? Any one for ideas??

Hi Grand

-i didnt really understood exactly the swapping-board order.. you mean that you tried a cabled gps on APM2 with the internal?? thats never going to work, because they share the same port..

-The blue light on APM2  kept flashing?? mine does that

-If you have the same symptoms, the solution was just reloading the firm?

Our temprature is about 20degrees C, so its not temp related for sure, a team member commented my issue, as a GPS-Antenna problem..

Hi James.

Re your 1st comment

I have an APM 2 without a GPS. I install the GPS on the UART1/GPS port. So I swapped cables to check that it was,nt the cable and then swapped the GPS unit itself with another unit which got lock using the UDB4.

Re your 2nd. Yes blue light just flashes indicating no 3D fix.

Re your 3rd. Reloading the firmware for the GPS or for the APM 2?

Your last comment. The ambient temperature was 20 degC higher than your 20 degC. Very hot.

Thanks for your response. Awaiting clarity on 3r point.


How do you power the board/GPS combo? Have you tried powering by USB (if so, different computers?)

I'm asking because I had big problems getting a lock when powering via my BEC integrated into the ESC. That went away after powering the GPS with its own voltage regulator.

Hi Andre

This may be the problem. Because for some unknown reason the APM2 regardless of jumper JP1 on the board needs to be powered from the input RC rails. I do not have room nor can afford the weight of another battery so I connected a two wire connection between the input and output rails so that the ESC/BEC could power the board as well. When I established 3d fix using the APM2 after reloading the firmware I powered the board using a 4.8V nicad battery pack and not the 11.1V lipo with ESC/BEC via the throttle output channel. Perhaps the regulator on the ESC is messing with the power regulator on the board supplying a noisy or incorrect voltage to the Media Tek GPS unit???

Hi GRant,
I ment the Apm2 firmware reloading if helped. Iam using a seperate 5v 7a Bec to a spare output with the jumber on.Everything worked flawlesly before, one day just stoped. Oh dont forget to mention, offcourse i aleeady removed the red cable from esc.
Thanks again, any advices?

Still having this issue.  No GPS lock no matter how long I wait.  Just a slow blue blink from the 3d fix light.

hi Jonathan,

I dont know if you read it in the issue report here, i went out on clear sky, removed all my gear from APM 2.0, connected to mission planner via usb and the board stated to find sats, reconnected all my gear and this time connevted via 3dr radios to MP. Now it works great again... 

give it a try, it might be a bug or something.. 

Not sure if you solved this issue for yourself, or the solution has been posted elsewhere, but after encountering this same problem, the fix is easy.

My problems were: When connected via USB, got good strong lock quickly (<2 mins cold) but when powered on-board via lipo, I got 3-4 sats and 9999hdp. I had the jumper removed as I was powering board from both ends, UBEC on the front end and ESC BEC on the back end.

Solution: Put jumper back on

Result: Good strong lock under all conditions, flight ready and via USB

Hope this helps others.

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