GPS Bug

[JST]

For a while now, I've noticed that the date in the Porsche is...off. It's off by a very weird amount, like 34 days or something (can't remember the exact value, but it's not a month or a year).

I mostly ignored it because the settings on the PCM 2.1 are not intuitive and I didn't feel like figuring out how to fix it.

Today, I dove into the manuals and forums to try and figure out how to set the date, and was surprised to learn that you can't. At all. The car is programmed to get date info from GPS satellites, and there is no manual override (even through PIWIS, the dealer computer). And there's no fix for the date problem, because it's related to a GPS bug that occurred in April of 2019 that's similar to the Y2K bug.

Which is all super weird.

https://static.nhtsa.gov/odi/tsbs/20...69751-0001.pdf

Note that this bulletin suggests that it can be manually fixed, but there seems to be widespread agreement that that isn't true.

EDIT: There is a potential hack involving disconnecting the Nav, setting the date, and reconnecting the Nav; that I haven't tried yet.

[clyde]

Originally Posted by JST

For a while now, I've noticed that the date in the Porsche is...off. It's off by a very weird amount, like 34 days or something (can't remember the exact value, but it's not a month or a year).

I mostly ignored it because the settings on the PCM 2.1 are not intuitive and I didn't feel like figuring out how to fix it.

Today, I dove into the manuals and forums to try and figure out how to set the date, and was surprised to learn that you can't. At all. The car is programmed to get date info from GPS satellites, and there is no manual override (even through PIWIS, the dealer computer). And there's no fix for the date problem, because it's related to a GPS bug that occurred in April of 2019 that's similar to the Y2K bug.

Which is all super weird.

https://static.nhtsa.gov/odi/tsbs/20...69751-0001.pdf

Note that this bulletin suggests that it can be manually fixed, but there seems to be widespread agreement that that isn't true.

EDIT: There is a potential hack involving disconnecting the Nav, setting the date, and reconnecting the Nav; that I haven't tried yet.

You could do the real fix by dialing 9-1-1.

[JST]

Originally Posted by clyde

You could do the real fix by dialing 9-1-1.

LOL, only if I get one with PCM 3.0 or better.

[clyde]

Originally Posted by JST

LOL, only if I get one with PCM 3.0 or better.

Sounds like a plan to me!

[wdc330i]

[Terri Kennedy]

Originally Posted by JST

Today, I dove into the manuals and forums to try and figure out how to set the date, and was surprised to learn that you can't. At all. The car is programmed to get date info from GPS satellites, and there is no manual override (even through PIWIS, the dealer computer). And there's no fix for the date problem, because it's related to a GPS bug that occurred in April of 2019 that's similar to the Y2K bug.

If you can get to the GPS firmware (that's the big question) it is a tiny, trivial fix. For example, the fix for the Qualcomm MDM9615 (a "kitchen sink" chip that combines cellular radios with GPS, and used in places like the iPhone 5) is only 804 bytes long and was released on September 4th, 2018 - long before the bug would happen in the real world (I know this because I just updated a bunch of new-old-stock mobile broadband cards).

The GPS chipset manufacturers made this available to their direct customers, who were then responsible for getting it installed in their products. That last part is where your Porsche seems to have "fallen through the cracks" - whoever made the navigation system (Visteon or some similar company) either didn't bother creating an updater for their installed equipment, they didn't supply it to Porsche, or Porsche decided to not bother releasing it.