Pcm2.1 can see 6-7 satellites but incorrect location

[Willow5]

My PCM2.1 is showing 6 or 7 satellites but displays an incorrect location in a completely different city to me. I have tried the 1-4-8 reset procedure but this hasn't helped. If it can see satellites, could there still be a problem with the antenna? For information, I also have a problem with the date and it displays the year 2000. When I go into the time/date settings on the PCM, it says "no GPS data is available" so I am really unsure whether true GPS data is available despite the unit seeing 6 or 7 satellites.

Edited January 3, 2020 by Willow5
Typo

[Rick150]

You have a clock that can be manually set but the update of the time is constantly corrected by GPS signal. You need 3 satellites to know where you are, 4 is better at least 90 degrees apart for 2 satellites.  Your location is calculated by transit time of the clock signals relative your correct time. Your  internal GPS has an almanac of where satellites should be so the search is quick as possible when the system is turned on. If your system shows the incorrect position then it is not receiving the timing data from acquired satellites and maybe using the outdated almanac.  Maybe it is a bad antenna, I am not sure how the system works in the Porsche but GPS requires synchronisation of time to work. Could be something so simple as reinserting the plug back into the PCM as the signal acquired is very small and any attenuation makes the signal unusable. Your clock defaulting to 2000 is a good indication of not resetting timing data as year 2000 it the base datum for calculation.

Your unit seems to be using old internal data.

Regards Rex

 

Edited January 4, 2020 by Rick150

[Willow5]

Thanks Rex, forgot to say that I recently replaced the PCM as the last one was completely broken. I have the same model (BE6654) but a slightly older revision 7l5.035.191H as opposed to 7l5.035.191K. How could I get the unit to refresh its brains?

 

It also appears to be using data from where the previous owner lived even though it is nowhere near them anymore so to me it appears to be using data from the car rather than its own memory. Is this even possible?

Edited January 4, 2020 by Willow5

[Rick150]

It will be using last known good position but won't navigate until it gets an update via a satellite. First thing it will do is synchronize the car clock then the car unit will read the almanac of the latest satellite positions that should be near you rather than the car unit searching for the whole constellation. So, if it is not even updating the clock even after reset then you have to check your antenna. Also if it's a little deaf get away from a built up area to lower the noise floor to somewhere  you have a clear look at the horizon above 10 degrees. If your clock gets a timing signal you probably have a bad antenna connection or something like that.  If nothing then something unplugged?  You better to ask a marine service guy as they deal with GPS issues all the time.