GPS Showing wrong location?

[erykv1]

Hey all,

Are there any solutions to fixing the NAV unit that is displaying the wrong location?
I have checked to ensure that it is not on DEMO mode. It was working fine a few days ago :(
When checking for satellites it displays 0.

I have already tried the reset multiple times by pressing the 3 button sequence and it doesnt seem to have done anything.

My software version is HN+_US_AU3G-K0942_6, is there anything else I should check before taking it into the dealer? Vehicle is a b8.5 allroad.

Thanks!

[Smac770]

Scan for DTCs, see if it knows there's a problem talking to the GPS antenna (part of the roof antenna).
The R50 GPS antenna in that roof unit runs a direct wire to the back of the J794 information electronics module. The J794 is the unit in the dash with the door and sd card slots and such. You could use the removal keys to pull it out and plug/replug that antenna wire (plug T1n) in case it's simply come loose. My rear view camera developed a problem after years, turned out the plug on the back of the dash unit was loose; unplug replug all good again.
But it could be the antenna, the wire, the connections on either end, or something broke in the J794 itself.

[erykv1]

Scan for DTCs, see if it knows there's a problem talking to the GPS antenna (part of the roof antenna).
The R50 GPS antenna in that roof unit runs a direct wire to the back of the J794 information electronics module. The J794 is the unit in the dash with the door and sd card slots and such. You could use the removal keys to pull it out and plug/replug that antenna wire (plug T1n) in case it's simply come loose. My rear view camera developed a problem after years, turned out the plug on the back of the dash unit was loose; unplug replug all good again.
But it could be the antenna, the wire, the connections on either end, or something broke in the J794 itself.

Just scanned for DTC's and nothing. I tried to connect to the nav module (menu option 57) via VCDS but it said it could not connect.

I ordered some radio keys off amazon and will try to check the simple things before taking it in later this week.

Thanks!

[Gunnark100]

I tried to connect to the nav module (menu option 57) via VCDS

You mean 5F?

[mtroxel]

I tried to connect to the nav module (menu option 57) via VCDS but it said it could not connect.

You mean 5F?

I'd bet he means 37. There is a module 37 - Navigation. The B8 doesn't have that. The Nav is in 5F - Information Electr as Gunmark100 was suggesting. See if there are signal error codes in that module.

[Smac770]

Address 37 (Navigation) is the J401 DVD drive in a MMI 2G vehicle (like mine).
Address 07 (Control Head) is the J523 "FID Control Head Control Module", called "interface box" in ETKA. Thus the terms you see in a scan of that address.

You won't have these in a MMI 3G vehicle.
The functionality of multiple modules, such as the J401, were integrated into the J794, which replaced the J523.

Address 5F (Information Electr.) is the J794 information electronics control module in a MMI 3G vehicle.

[erykv1]

You mean 5F?

I'd bet he means 37. There is a module 37 - Navigation. The B8 doesn't have that. The Nav is in 5F - Information Electr as Gunmark100 was suggesting. See if there are signal error codes in that module.

Address 37 (Navigation) is the J401 DVD drive in a MMI 2G vehicle (like mine).
Address 07 (Control Head) is the J523 "FID Control Head Control Module", called "interface box" in ETKA. Thus the terms you see in a scan of that address.

You won't have these in a MMI 3G vehicle.
The functionality of multiple modules, such as the J401, were integrated into the J794, which replaced the J523.

Address 5F (Information Electr.) is the J794 information electronics control module in a MMI 3G vehicle.

You guys were right, i was scanning address 37 (perhaps this is incorrect). I have a 2015 model.

I will try to take a look at 5F today and see if it says anything.

My headunit pulling tools should arrive today and I will at least check the antenna connection before to see if its a simple fix.

[erykv1]

Hmm. Update / question.

Does anyone know where the GPS/NAV antenna is located for these vehicles? I did install a dashcam recently near the mirror.
I powered the dashcam on AFTER the car was started (rather than have it start with the car)... and the car picked up 7-8 satellites.

Coincidence? Or possible interference from the dashcam? Seems like a common spot used by b8.5 installs though.

[Smac770]

The GPS antenna is in the roof fin; see second post in the thread.
Have you repeated the experiment and it seems consistent? Does it lose the satellites after powering on?
The connection is an single shielded RF wire from the roof fin to the back of the J794. But maybe your device is creating EMI or other noise on the power lines and it's upsetting the J794.
Did you ever do a scan to see what the J794 had to say about the situation?

[erykv1]

If I power on the dash cam AFTER the car starts, it maintains 7-9 satellites without issue.

When I scanned it said "could not connect to module." I will do a few more tests before blaming it 100% on the dash cam.

[DeeInSeatown]

Somewhat of a thread jack, but I've had similar issues with the nav on my car too. It works fine, but will intermittently loose where we're located. Seems like it happens when we get a little ways from home, say outride a 30 or so mile radius from home. Seems as if antennae connection is intermittent. We'll be driving, and all of a sudden nav shows us in some totally nonsensical place. Do the 3 button reset and it just thinks we're starting from home and never finds us.

I did a fault code scan earlier today and just went back to look at unit 5F. No faults come up. Is there something else easy to check?

[erykv1]

Somewhat of a thread jack, but I've had similar issues with the nav on my car too. It works fine, but will intermittently loose where we're located. Seems like it happens when we get a little ways from home, say outride a 30 or so mile radius from home. Seems as if antennae connection is intermittent. We'll be driving, and all of a sudden nav shows us in some totally nonsensical place. Do the 3 button reset and it just thinks we're starting from home and never finds us.

I did a fault code scan earlier today and just went back to look at unit 5F. No faults come up. Is there something else easy to check?

when you check to see how many satellites are being picked up in the route menu, what does it say when it loses position?

[DeeInSeatown]

when you check to see how many satellites are being picked up in the route menu, what does it say when it loses position?

Was looking through options the other day in the navigation screen after you posted the info about # of satellites but I'm not actually sure where to find it. Is that a VCDS thing or am I just missing it in a navigation screen menu?

[Gunnark100]

Was looking through options the other day in the navigation screen after you posted the info about # of satellites but I'm not actually sure where to find it. Is that a VCDS thing or am I just missing it in a navigation screen menu?

ONFo8fz.jpg

or check in green menu, under navigation.

[DeeInSeatown]

ONFo8fz.jpg

or check in green menu, under navigation.

Found it...blue menu? Didn't realize there was another view above the current location address. At the moment, have between 7 and 8 satellites and it know just where I am. Will have to look when it craps out again.

[Gunnark100]

Found it...blue menu?

Yep in blue(nav menu) or in green menu(engineering)
gps.jpg

[DeeInSeatown]

Yep in blue(nav menu) or in green menu(engineering)
gps.jpg

Gotcha, don't have that view activated on my car...or I'm just not able to find it.

[Smac770]

That's the green "hidden menu" that you have to enable via VCDS coding. A search will show how to enable access to it.

[DeeInSeatown]

That's the green "hidden menu" that you have to enable via VCDS coding. A search will show how to enable access to it.

Thanks, knew I saw it somewhere but couldn't remember what it was called.

[Mithrandir]

Just going to piggyback on this thread you as I have the same issue.

Decided to get the issue diagnosed by the dealer and said the antenna will need to be replaced. Cost of the antenna is $700 + getting the antenna painted + labour = $1300 + taxes..... (Jeebus...)

At this point would it be better to find a used antenna and replace it myself (or mechanic/shop how can do it for cheap)? Go with the Aftermarket Android system unit display that comes with NAV?

[mtroxel]

At this point would it be better to find a used antenna and replace it myself (or mechanic/shop how can do it for cheap)? Go with the Aftermarket Android system unit display that comes with NAV?

I looked at the manual, step #1 is to remove the entire headliner. That's a pretty big job. But you could do it in a Saturday. My friends at wolfautoparts.com have some already painted for around $50. Check them out.

[DeeInSeatown]

Just going to piggyback on this thread you as I have the same issue...

At this point would it be better to find a used antenna and replace it myself (or mechanic/shop how can do it for cheap)? Go with the Aftermarket Android system unit display that comes with NAV?

That dealer price is ridiculous! What symptoms are you seeing, and are they intermittent for you as well?

[Mithrandir]

I looked at the manual, step #1 is to remove the entire headliner. That's a pretty big job. But you could do it in a Saturday. My friends at wolfautoparts.com have some already painted for around $50. Check them out.

Thanks! Will check them out.

Sent from my Pixel 2 XL using Audizine mobile app

[Mithrandir]

That dealer price is ridiculous! What symptoms are you seeing, and are they intermittent for you as well?

I do get a signal but at this point it defaults out to Greenland everytime I start the car but doesn't even show me an exact location. Use to show me before that I was in Memphis (I'm in Toronto Canada) and also show the cursor moving around.

Sent from my Pixel 2 XL using Audizine mobile app

[DeeInSeatown]

I do get a signal but at this point it defaults out to Greenland everytime I start the car but doesn't even show me an exact location. Use to show me before that I was in Memphis (I'm in Toronto Canada) and also show the cursor moving around.

Sent from my Pixel 2 XL using Audizine mobile app

I love the Nav showing me driving in the water. Mine's an intermittent failure, and usually just crops up when a little ways from home and outside my normal driving range. Can't tell you how many times I've been bushwhacking across city grids or driving in the Puget Sound, according to the NAV that is. That's not my typical real life driving behavior.

[Smac770]

You're a beta tester for that new Audi auto-boat conversion?

[DeeInSeatown]

You're a beta tester for that new Audi auto-boat conversion?

Yeah, who knew. Quattro really gets it done!

[erykv1]

I'm throwing the towel in. Since I made the thread, I brought it into the dealer... and of course the day I bring it in, it starts working.
So they found nothing and it worked for a few weeks. Tonight it lost satellites again.

Looks like I will use this as an excuse to pick up an RSNAV.

[Militant-Grunt]

I'm throwing the towel in. Since I made the thread, I brought it into the dealer... and of course the day I bring it in, it starts working.
So they found nothing and it worked for a few weeks. Tonight it lost satellites again.

Looks like I will use this as an excuse to pick up an RSNAV.

Before you do that, you most likely may just need a coax wire repair. The coax wire at the antenna connection gets kinked and causes a intermittent open circuit. We cut the wire a couple inches back and crimp on a new connection and then use a short patch cable to introduce slack into the harness.

When I diagnose these, I generally run my own cable between the 5F and antenna for testing, if that doesn't solve it I then have a tester antenna. There is also a small possibility that the port on the 5F is dying. Statistically it goes Coax repair > Antenna > 5F

[erykv1]

Before you do that, you most likely may just need a coax wire repair. The coax wire at the antenna connection gets kinked and causes a intermittent open circuit. We cut the wire a couple inches back and crimp on a new connection and then use a short patch cable to introduce slack into the harness.

When I diagnose these, I generally run my own cable between the 5F and antenna for testing, if that doesn't solve it I then have a tester antenna. There is also a small possibility that the port on the 5F is dying. Statistically it goes Coax repair > Antenna > 5F

Yep you are correct.

I bought a $15 antenna off ebay to just test if I would get my satellites back.

...low and behold it immediately picked up 6 satellites (I didnt bother putting the reciever in an open location since I was just testing, its just shoved behind the MMI for now).

I'll keep an eye on it for this week. Thanks for the suggestion.

How would I know where on the cable needs repair?

[Militant-Grunt]

Yep you are correct.

I bought a $15 antenna off ebay to just test if I would get my satellites back.

...low and behold it immediately picked up 6 satellites (I didnt bother putting the reciever in an open location since I was just testing, its just shoved behind the MMI for now).

I'll keep an eye on it for this week. Thanks for the suggestion.

How would I know where on the cable needs repair?

Most likely right at the antenna, from the factory they are not given sufficient enough slack, though its possible it could be at the 5F as well. 9/10 times its at the antenna. To perform the repair you need a special VAS tool kit, no idea if there's a aftermarket equivalent.

[Smac770]

https://www.ecstuning.com/b-genuine-...4g0035503kgru/

It's just a FAKRA plug and RF cable. One to the radio (sat radio R170), two to the J794 (GPS R50 and cellular R65). No idea which color goes to which. It looks like there's pigtail leads that attach to the R52 roof aerial and then a join to the longer wire running to the front or rear. Kind of looks like the join for the video cable from the parking camera to its cable.

Here's an idea of what you're looking at. https://www.ebay.com/i/392064375069
But if it is the main cable run that has a problem end, yeah, probably better to redo the end. And for that, you would need a FAKRA crip tool.