GPS not holding signal

[BottomScratcher]

I've had a look here and on other forums, but still need help. My Columbus (RNS-510) Satnav has me flying over water, or crashing through bush, or houses and backyards for whole blocks. Sometimes I'm 300m or so ahead of where the GPS is positioning the car, or I'm two kms away from where I'm shown to be on the satnav map. Other times it's working normally.

Just wondering if anyone has had any experience of this problem. It's only been doing it a few days. I know I only need 4 satellites to get a 3D fix, but the fewer satellites the slower the unit is to respond. Sometimes I'm holding 5 or 6 out of 11 or 12 satellites, and other times it's none out of 11 0r 12, and that's when the "flying" starts". I suspect a GPS antenna problem, but that's where I get confused. I looked for info on the antenna, and see that it's the blue FAKRA connection on the back of the head unit. There is much mention on other forums of the antenna "puck" being located on top of the glove box on factory fitted units, which mine is (standard on MY11 and later), but I thought the GPS antenna was incorporated into the roof top fin/whip antenna.

I pulled the head unit out and the centre dash air vents. The antenna cable disappears into a thick loom that goes into a hole near the bottom RHS of the glove box, which I'm thinking goes via the hood lining to the roof antenna. I removed and replaced the connection before refitting the head unit.

Why the long winded post? The car is under warranty, but I really don't want a dealership workshop pulling the glovebox or the hood lining, or be without the car for ??? if I can do a simple and relatively inexpensive fix myself. I was thinking of buying a puck antenna and sitting it under the dash between the head unit and the centre the air vents. Remove trim, undo 4 screws, pull the head unit out far enough to change antenna connections, put on a bit of double sided tape, and Hey Presto! All well and good if it is the antenna that's causing this intermittent problem, BUT is it possible that it could be a firmware issue? Thanks.

Part: 3T0035680B

HWV: H42

SWV: 3974

Maps: 7920

[kamold]

Yours is factory fitted, so there is no puck antenna. These are for aftermarket installs.
Your antenna is connected to the roof via the loom that you saw.

It is possible that there is some corrosion in the antenna connection in the roof if the antenna connection to the back of the RNS is secure.

Yes you can certainly confirm this by temporarily fitting a puck antenna and either sitting that on the dash for maximum satellite exposure, or mounting it under the dash as you would if you were retrofitting your RNS.

Then you'll know if you need to take it in to have the roof antenna connectors examined.

Not a firmware issue.

[BottomScratcher]

Thanks kamold. Now I get it. The puck is retrofit. To be a PIA (I stick with my strengths), am I right to think that the flat flat bit of the roof fixture is the GPS, the phone antenna is in the fin bit, and the whip is for FM radio?

Having ruled the firmware out I'll get an OEM puck antenna from the UK via eBay. If it fixes the fault I'll just tape off the original connector and leave it at that. Thanks again mate.

[kamold]

Correct the GPS antenna is oriented horizontally in the fin to 'look' up at the satellites.
It will give the best possible reception as it is uninhibited by any other part of the car.

That said the pucks do perform well 90% of the time if well placed. At least it will let you know the issue lies in the external antenna/connector if it does work. If it does I would be inclined to get it replaced under warranty. Its a relatively straight forward remove/replace that doesn't mess with dash or door trim which can end up rattly/squeaky if not handled correctly.

[BottomScratcher]

Thanks for that. I know you're right about getting it done under warranty. It's just that in my experience I don't recall too many hood linings that have been removed that go back as neat as they were before and stay there. Times change, so I should have a little faith I suppose.

[Hillbilly]

Someone else had the same problem a few weeks ago and the problem was a connector under the carpet beside one of the front seats Whichever side the loom goes down Look through the GPS threads he even posted a photo of the yellow connector Doesnt need the hood lining removed apparently as there is a connector underneath the fin


This Thread GPS is off Posts 42 and 48 are relevant

[kamold]

Someone else had the same problem a few weeks ago and the problem was a connector under the carpet beside one of the front seats Whichever side the loom goes down Look through the GPS threads he even posted a photo of the yellow connector Doesnt need the hood lining removed apparently as there is a connector underneath the fin


This Thread GPS is off Posts 42 and 48 are relevant

This.
Was trying to remember what the previous issue was.
Thanks Hillbilly

[BottomScratcher]

G'day Hillbilly,
Thanks for that. Looks like I'll eventually have to take it to the dealer for an antenna changeout, so I may as well bite the bullet, and contact them today. I read the post #42, and was all smiles and expectations. Mrs BS never moves the pax seat around unless there's someone in the back,... like there was on Saturday when the problem started. Then I read post #48, and realised that I wasn't going to get out of it so easily.

Still, I appreciate you pointing me there. Every time I try to use the "search" it doesn't matter what word/words I type in I always get 27 pages of threads all starting with "What did you do to your Polo today".

[BottomScratcher]

The GPS antenna is faulty. I've been running a puck antenna under the dash for a couple of weeks, but got the car to the dealer to be told that there is a TPI (VW jargon for Service Bulletin) on ERWIN for certain part numbered antenna's, and mine is one of them. I was also informed that there's a revised replacement antenna (New And Improved!!!) that must be fitted to replace those specified under the TPI.

[kamold]

Any word on if the replacement is a sharkfin, or another bee-sting?