My Columbus satnav (RNS-510) just went bonkers

[Poltroon]

I have a factory installed Columbus in my MY2011 Octavia. The satnav has suddenly gone mad. The map tells me I am about 2 km from where I really am. And the compass has me facing about 90 degrees different from reality.

The audio/radio etc all seem to behave as normal.

The GPS is showing 0/10 or 0/11 satelites, occasionally it finds 1/11. So my assumption was that the antenna had somehow failed. But would this also affect the compass? Does the unit figure out the heading from the satelites or is there an old fashioned compass in there somewhere?

The gyro seems to work as when I drive around the map and direction change as expected ... except that they have me in the wrong place.

I've tried sitting in an open area for a long period to see if it can acquire any satelites but it never finds more than one.

It worked perfectly until a few days ago.

Any ideas?

[kamold]

There is no compass. It just calculates heading from the GPS position and speed info.
Pull the RNS out and check the antenna connection at the back.

Actually first check the antenna connection under the seat (I think passenger's seat from memory?) This has been known to come loose.

Check this thread

Failing that there was also a TPI for some antenna, there was a revised part released. Would have to check with a dealer to see if your VIN is affected.

[Poltroon]

Thanks for that thread, don't know how I missed that before.

So, it sounds pretty certain that I have an antenna problem. I couldn't find a cable join under the seat, but I'll have a better look when I have some better lighting. Meanwhile I gave the roof antenna a shake just for fun and was surprised to see lots of water run out from under the rubber gasket. The car has stood out in the rain for several days, so I'm thinking maybe water in a connection at the antenna end. I can't find any diagrams online, but some photos for a golf show about 300mm of coax before a cable joint, so unlikely to have water that far from the base of the antenna I would have thought. I'm not looking forward to trying to get the antenna off the roof, looks like the internal roof lining will have to come out.

... there was also a TPI for some antenna, there was a revised part released..

Do you know the implications of a TPI when my car is way out of warranty? Can I expect any "help" from a dealer with this?

I've got a service due shortly so I guess I'll soon find out.

[kamold]

No harm in asking.

Sent from my HTC One_M8 using Tapatalk

[Poltroon]

Just to close this out (in case anyone else has a similar fault) ... the problem was indeed the GPS antenna.

There is a TPI (service bulletin) describing a known problem with the roof antenna, but my VW dealer was not interested in helping with replacement since the vehicle is out of warranty. He quoted $181 for the new antenna plus min 4 max 12 hours to replace it. In practice I bought the new antenna online for half that, and it took me about 1 hr to replace it.

The original p/n was 1K0 035 501 F. The updated p/n is 6R0 035 501 C . I bought it from Cars Equipment s.r.o. and it took about 2 weeks delivery from Czech Republic.