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Joined: 17 Feb 2015
Posts: 56

PostPosted: Thu Feb 28, 2019 9:04 am    Post subject: Dash PCM Date gone missing! Reply with quote

Hi All

Anyone else had the date in their dash disappear recently? Mine in my 997.1 Targa4 has gone and I can't get it back? Tried all sorts to reset it and factory resets, etc.

Anyone know the issue and possibly the fix?

2008 Black 997 Gen1 Targa 4
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Joined: 22 Jul 2013
Posts: 127
Location: Shropshire

PostPosted: Thu Feb 28, 2019 5:13 pm    Post subject: Reply with quote

Here is the reply from Richard Hamilton who is somewhat of an expert on the Porsche 'infotainment system' after I asked the question of him,

This seems to be getting more common with PCM2.1 units. I have no idea why it is happening. There was a mention on one forum of some kind of time signal reset on the GPS system, which many older satnavs may not be able to cope with. A bit like the Millennium Bug for computers (which never happened). However, the date this will happen is 6th April: https://www.theregister.co.uk/2019/02/12/current_gps_epoch_ends/

It often seems to happen after disconnecting the battery, or a flat battery. I have also heard of units suddenly start displaying the time after some days, weeks, or months have passed.

You can try a system restart by pressing the 1, 4, and 8 buttons at the same time, but I have no confidence it will do the trick. Sorry I can’t give you a positive answer.

Porsche Carrera 2S 2005 black fully Hartech'd!, BMW Z4 coupé 2007 blue, Mazda Eunos 1996 yellow, VW Passat 2014 black.

We all do silly things/make mistakes, it's how we deal with them that sets us apart from animals and Americans.
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Long Beach

Joined: 08 Jan 2011
Posts: 6966
Location: Nottingham, England

2004 Porsche 996 Turbo

PostPosted: Thu Feb 28, 2019 5:44 pm    Post subject: Reply with quote

GPS time is stored as a 10 bit week number, millisecond of week, and another byte(I think) for the multiple of 10 bit week number. It is the week number multiplier which is changing. If this is not used correctly the date will be off by exactly 1024 weeks.

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Long Beach

Joined: 21 Mar 2015
Posts: 6523
Location: Brighton

PostPosted: Thu Feb 28, 2019 6:40 pm    Post subject: Reply with quote

Ive not seen this particular problem but i have seen other faults such as heated seats not working after a battery replacement ..

We do a Vehicle handover useing a tester .. it kinda resets / wakes up all the control units and is a common thing to try with any fault upto current models ....

Especially if its software related like this seems to be .

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