GPS Signal Way Off After driving for a bit

I recently upgrade my 2015 F150 MFT to a 2020 F150 non-nav APIM with Sync 3.4.23088. I am using original 2015 ACM and almost everything works flawless after the Forscan changes. The only issue I have is after about 30 to 40 minutes into a drive the gps location goes crazy showing me way off course. The first thing I did was move new Sync 3.4 fakra gps antenna from the top of old gps module under dash to above the dash under windshield. This seemed to fix the gps issue. I didn’t like the gps puck being on the dash so I decided to purchase the Ford GPS antenna splitter. It takes signal from roof mounted gps antenna and splits it. There is a mustard colored connector for Sirius that goes into ACM and a blue connector for Sync 3.4 APIM. This also cured the gps location issue. I thought everything was fine until I noticed that the time at the top of screen with the temperature is way off now. I went into settings to set the clock with gps and it says gps unavailable right now. I then set the clock manually but when I exited out of settings the clock reverts back to 12:00. I then reconnected the cheap square gps antenna to the Sync 3.4 that is on the dash and now the clock updates correctly. Can anyone tell me what is going on? Is the 2015 oem roof gps antenna not capable of receiving clock data? If not can I get an updated oem roof mounted antenna that will remedy this issue? Thanks so much for the help.

SYNC Region: NA

Navigation Variant: Non Nav

Manufacturer Year: MY20

Install Type: Retrofit

Old SYNC Version: 2

New SYNC Version: 3.4

Do you have a error message, if so what is it?
“GPS data is unavailable right now” When I try to set clock with GPS but all Carplay navigation apps(Apple maps, Waze, Google Maps, ect) work correctly.

Update Method: CyanLabs Syn3 Updater

Syn3 Updater Version: 2.0

Syn3 Updater Documentation Read: yes

Syn3 Updater Log File

[log.txt|attachment](upload://yomhDdsJJiaF8ilV1sp7a8AD0Cq.txt) (1.9 KB)

There is nothing wrong with the OEM antenna splitter you are using. More than likely the antenna was not built to receive that type of signal. You can swap it with a 2017 antenna and that should solve the issue.

Do you have Sirius?

I was thinking the same thing but wanted to hear it from another person. I was thinking maybe the 2016 antennas were made to receive both types of signals. I will order a 2017 antenna. I do have Sirius. Not SiriusXM but from my understanding the antenna type shouldn’t matter. Am I correct about that?

I’m inclined to agree. If your 2015 had the factory GPS module behind the dash, the roof antenna won’t have the antenna hardware needed that the splitter would go with.

That said, I do recall seeing a thread on the F150 forums (sadly can’t find it now) where many have upgraded to a 16+ roof antenna that does have the GPS antenna built in and works fine with the splitter you have. So that is an option if you want a more factory style setup.

I had the same issue with several Explorers. Swapped out for antenna’s that looked identical but newer and it solved the issue.

I found that the splitters were for the most part all the same.

I really appreciate the replies. I definitely would rather have a factory setup even if it costs a little more. Especially since I have already had location accuracy issues with the cheap square puck type antenna that most use for Sync 3 upgrades. I think it’s accuracy is suspect because when placed under the dash, it doesn’t have a metal ground plain to sit on. I guess I could make a ground plain but I would rather have a more factory setup. Thanks again for the confirmation.

I do have one last question. Whenever I unplug the the old 2015 GPS module under the dash the compass in the IPC goes blank. Do I need to keep the old module under the dash hooked up for the compass in the IPC or is there a Forscan change that allows the IPC to get the direction from the APIM?

I am not 100% familiar with the F150’s but that sounds like you have the CGEA 1.2 network in your truck. You would need to keep the Antenna in as the IPC does get the direction from that GPS antenna. Once you get the OEM one in with the splitter it will all be fine. The SYNC 3 units look for the GPS signal from the new antenna so it should not conflict.

Thanks for the reply Bill. I’ll report back when I get the new oem gps antenna installed to let you guys know for sure and for any future forum searches.

Update: Just wanted to update those that care. Replacing my oem roof mounted gps antenna with a newer oem gps antenna fixed my gps location being way off at times.
I ended up replacing my 2015 F150 oem roof mounted gps antenna with part # JL3Z-10E893-AB(Tasca says it fits 2018-2020 models). I then used the Ford GPS signal splitter harness(GL3Z10E928AA) installed behind the APIM & ACM to split the signal. The blue connector went to the 2020 year model APIM and the yellow connector went to the original 2015 ACM with Sirius satellite radio. I then removed the cheap square puck gps antenna that people normally use for Sync 3 upgrades. I know the cheap antenna works for some but it was not working all the time being under the dash and I didn’t want it visible on the dash. For this reason I went the oem antenna and splitter route. Originally I tried to use the gps splitter harness with original antenna but then the APIM couldn’t set and maintain the correct time of day. Apparently the old roof mounted antenna couldn’t provide the clock information to the APIM.
WARNING: You will need to slightly enlarge the hole in the roof for the newer antenna to fit. The mounting stud on the newer antenna is slightly larger and not exactly round. Thanks for all the replies to my initial question that helped lead me in the right direction.

Good to hear. I think the larger hole might be on a case-by-case basis as I have not had to do that on a couple of cars I have done.

Glad it worked for you. A few others that have ditched the crap Chinese connectors have been much happier.

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