GPS not tracking correctly

P

paulo

Member
 Japan
GPS seems a little off and not in the correct place. I have to manually move the car to the correct spot after I park it overnight. Otherwise, it seems to be mostly ok with directions. The dealer told me for him the GPS was very far off and even a small amount of driving caused a big movement on the map.

No windshield replacement. It's a 2010 car. Would love to get this fixed. Could this be a antenna issue or a head unit issue?

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Usually its an antenna fault ..no wiring disturbed?

But..could be the motherboard too!
 
Has it always done this or only just recently? Its possible for the powers that be to degrade GPS accuracy at certain times. Also I'd expect it to be seeing a lot more that four satellites. That's the minimum needed but I'd expect to see more like seven or eight to give you sub10 metre accuracy. .
 
Rockhopper said:
Has it always done this or only just recently? Its possible for the powers that be to degrade GPS accuracy at certain times. Also I'd expect it to be seeing a lot more that four satellites. That's the minimum needed but I'd expect to see more like seven or eight to give you sub10 metre accuracy. .
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Its Japan so doubt its spoofing or jamming
 
Yes I'm in Japan. I would assume widespread reported issues if that were the case.

So I should start with replacing the antenna on the windscreen? Any other tips to pinpoint the issue?
 
Not an e89 but had the same issue with my e86 when I bought it. Was getting signal, car on map was just ~200 miles away. Replaced the antenna and that did the trick.
 
So today I've had between 4-8 satellites and 3D lock without any issues. I wonder if it had to do with the car sitting at the dealer for a few months before being driven for any distance again.
 
paulo said:
So today I've had between 4-8 satellites and 3D lock without any issues. I wonder if it had to do with the car sitting at the dealer for a few months before being driven for any distance again.
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That was a crucial piece of data you omitted!

Time to first fix TTFF is highly dependent on the status of the GPS almanac stored in the GPS receiver…if it’s out of date then the GPS needs to do a back to basics basic first fix..with old GPS units even in clear skies that could take 20+ minutes…start moving or have an obstructed sky (Japan anyone) and it may never get a first fix..
 
I drove for 100km first two days in unobstructed sky both in the outer city and countryside, so I expected it was not the issue. I will keep an eye out on it for the next few days.

One thing I did notice today is I feel it still lags behind a little based on where I am vs where the red triangle is - like a car or two distance or so.
 
Car or two is what i have always seen on my cars gps. Not good coming up to multiple junctions.
Keep in mind the technology in the car is probably 20 years old.
Lag might be just the screen.
 
paulo said:
I drove for 100km first two days in unobstructed sky both in the outer city and countryside, so I expected it was not the issue. I will keep an eye out on it for the next few days.

One thing I did notice today is I feel it still lags behind a little based on where I am vs where the red triangle is - like a car or two distance or so.
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My unit would not get a fix for several days..only after leaving it a car park for 2 hours with no visible limits..if the car is moving it won't get an initial FF..

Gyro may be duff too!
 
How can you tell if the gyro is duff? Will it throw up error codes? I will get my reader this week.
 
A more common problem than you think, and a very frustrating one at that. The CIC system was used on a lot of models, 1, 3, 5, 6, 7, X1, X3, X5, X6 Z4, and now time is going on for them all there are a lot of posts regarding this same issue.

There are four main points of failure...
1) Windscreen mask failure (less likely).
2) Antenna failure (most common).
3) FAKRA cable damage/failure.
4) GPS receiver PCB board in the CIC unit.

1) Possibly something is interfering with the reception around the windscreen mask (the black section above where the rear view mirror goes). This could be something like a metallic sticker or electronic device.

2) Yes the antenna can fail. Here's one specifically for the E89...
www.ebay.co.uk

BMW Z4 E89 Roof Antenna Aerial Shark Fin GPS 9123783 | eBay UK

Part no: 9123783. We will ALWAYS try our best to help. It is also possible to collect the item from UK warehouse. This item is used but is in good condition and is in full working order.
www.ebay.co.uk

And the exact same item from the 4 series (you would just remove the metal bracket)...

3) The cable running from the antenna to the CIC unit (runs to the right side of the antenna, down the right side A pillar and over to the CIC unit), can get damaged, although very rare unless anyone has done some work on the car, or could be having interference from another source.

4) Unless you can find an electronics shop that know their stuff then it's a replacement CIC headunit. This would then need coding to the car.

Hope that helps :thumbsup:
 
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