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      06-16-2021, 08:04 AM   #1
GyroF-16
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GPS antenna on a Coupe?

The GPS Nav in my M Coupe has been “getting lost” lately. It usually starts at the correct location, but gets confused on position when I start driving. And no elevation reported (which implies to me that it’s not seeing enough satellites to get a good 3D position fix).

I’m wondering if the antenna is the problem.
Anyone know where it’s located on a Coupe?

Possible contributing factors:
- I pulled panels in the trunk last week and installed a BlueBus. I didn’t disconnect anything unrelated to the audio (two CD changer related plugs). But it’s conceivable I dislodged something without knowing it.
- I also inadvertently ran the battery down while troubleshooting the BlueBus. It’s recharged now. Could something in the GPS system need resetting to work correctly?

Anyone have ideas? Or some guidance for troubleshooting the GPS? Is there a way to get into a diagnostic mode where I can see how many satellites it’s seeing at a given moment?
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      06-16-2021, 10:20 AM   #2
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I'm not 100% sure for a coupe, but if it's like the roadster the antenna is hidden in the trim above the windshield. It's a pretty common problem with all the models that use this antenna. I replaced mine years ago because it wasn't even close, once even showed me a couple of miles out to sea.
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      06-16-2021, 12:17 PM   #3
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Thanks, Nate.
I found instructions for doing the diagnostic mode
http://mr-fix.info/hidden-menu-bmw-navigation-mk3-mk4/

So I’ll check that out this weekend and see if I can narrow down what’s going on.

RealOEM wasn’t much help finding the antenna - it shows the part and the cable, but no context for location. I’m hoping it doesn’t involve pulling the headliner...
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      06-21-2021, 04:04 PM   #4
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Update:
Used the diagnostic menu and determined that:
- my GPS doesn’t know it’s Lat/Log (they’re blank)
- thinks it’s 5.11.01 with the wrong time (but the minutes past the hour are correct (and it’s not giving me GMT time)
- is not seeing any satellites (although one display thinks it’s seeing (or looking for) 8 - but has an S/N of 0 for all of them).

The last two times I drove my car, the initial location seemed right, but the displayed location moved in the wrong direction as I began driving, and got progressively further from the actual location.

I’m thinking either the GPS antenna (or the connection to it) has failed, or the GPS computer’s almanac got reset when my battery died (see earlier post), and it’s looking for the wrong satellites.

Can anyone confirm that the GPS antenna is behind the light panel above the rear-view mirror in a Coupe?
Anyone have suggestions for how to reset the GPS computer or almanac to help it know which satellites to look for?

Thanks in advance!

Last edited by GyroF-16; 06-21-2021 at 04:12 PM..
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      08-08-2021, 08:33 PM   #5
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Quote:
Originally Posted by Nate4641 View Post
I'm not 100% sure for a coupe, but if it's like the roadster the antenna is hidden in the trim above the windshield. It's a pretty common problem with all the models that use this antenna. I replaced mine years ago because it wasn't even close, once even showed me a couple of miles out to sea.
Nate-
I’ve located the GPS antenna in my Coupe… it’s behind the dome light / map light panel that’s right above the rear-view mirror.
Trouble is - I haven’t been able to get it out. I can wiggle it in the mounting bracket, but don’t know how to release it, or which way to slide it off.
I considered just leaving it in there, and plugging in the replacement antenna I bought on Amazon, but can’t disconnect the cable, either. It disappears in to the headliner going towards the driver’s side. It’s pretty firmly attached to something over there, as it didn’t budge with a few tugs.

I’m starting to suspect that I may have to pull the headliner down to get the access that I need.

But before I do that, do you remember anything about how you released and unplugged the OEM antenna? I’m hoping not to make it any more involved a task than it needs to be.

Thanks in advance for any help.

Inputs from others are welcome and appreciated, as well.
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      08-17-2021, 09:36 AM   #6
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Quote:
Originally Posted by GyroF-16 View Post
Nate-
But before I do that, do you remember anything about how you released and unplugged the OEM antenna? I’m hoping not to make it any more involved a task than it needs to be.

It's been a long time since I replaced mine so I don't remember exactly. I remember there being some metal on one side of the connection for the antenna, and looking at pictures online I still can't tell if it's threaded or just a tight collar.
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      08-27-2022, 08:04 PM   #7
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Okay- I’ve resolved this issue…
When the battery died, the Nav computer evidently reverted to “Transport Mode”.
When I had the car at the local BMW dealer for a tech inspection prior to a BMWCCA HPDE.
They hooked it up to their computer, found it in “Transport Mode” and switched it out of that mode.

Nav system is fully functional again.

FWIW, it’s evidently common to have the car revert to “Transport Mode” after a battery failure. It’s often accompanied by the Air Conditioning to also stop working in that mode.
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      11-02-2023, 07:02 PM   #8
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Interesting. So was this even after you swapped in the new Antenna? My nav is showing the same issues, and the OCD in me wants to get it working even if I don't use it.

Quote:
Originally Posted by GyroF-16 View Post
Okay- I’ve resolved this issue…
When the battery died, the Nav computer evidently reverted to “Transport Mode”.
When I had the car at the local BMW dealer for a tech inspection prior to a BMWCCA HPDE.
They hooked it up to their computer, found it in “Transport Mode” and switched it out of that mode.

Nav system is fully functional again.

FWIW, it’s evidently common to have the car revert to “Transport Mode” after a battery failure. It’s often accompanied by the Air Conditioning to also stop working in that mode.
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