Terry Adams

First pic is with the correct time, 9:58

Insert key and turn but not engine on = correct time.
Turn engine on = time jumps ahead.
Drive a mile or so = clock reverts by itself to correct time.
Been happening since Porsche dealer replaced battery last service visit.

bondjockey

Brainz

Mine does this too. I suspect the clock is voltage sensitive, but not sure as the car stays on a tender, so the battery is always topped.

Terry Adams

A further observation this morning:

Clock jumping ahead happens at first start, first time the Tip selector lever is brought backwards out of park. To R or N or D.

Not in a hurry to get it to Porsche dealer. Was worried before about a stall due to poor connection somewhere.

Brainz

Appears the clock is set by GPS. I wonder if it gets confused at night. Once the GPS locks, all is good. I thought there was a way to turn off the auto time update, but I couldn't figure out how to do it - - I didn't check the manual, just punched all the buttons.

Terry Adams

Clock set by GPS might be it, since first start is in the garage, except that

first time this happened in 11 years, and

if it's set by GPS, I would not have to do a manual reset for DST

Will update if I get more.

Turboslut

Mine has been doing this lately as well

o7silverturbo

remove both battery cables and touch them together for five-ten minutes. This lets all the computers drain down.

Re-install battery cable and re-test

Terry Adams

Thanks. Will give it a try.

Ruskiy

Any luck?

Misplacedyankee

This has happened on all but my 991 porsche. My 996 did it, all three 997s.I think the Boxster did it too. Great cars, bad clock. Honestly until lately I have never been impressed with P-car electronics - air bag light, the stereos in the 996s, the belt sensors - all just problematic. Change a battery and you have to wait for the PSM malfunction lights to go out - its even in the manual they knew it was goofy.

Terry Adams

Not yet. Don't laugh, kinda scared to try it. Am 35 minutes two truck from dealer if something strange happens.

Have a dealer visit for tires in a few weeks, will schedule with that. Will definitely report back when I do it.

o7silverturbo

I promise you there is nothing to worry about.

I perform this kind of "reset" all the time on many different kinds of cars.

Sometimes computers just lose their memory or get confused. Its just like doing a hard reset on a desktop computer

Terry Adams

Attempted the reset just now. Cables were about 6" too short to touch together, so left them sit for 10 minutes unconnected.

Think it fixed the clock, but won't know probably til tomorrow morning at first start.

Got lights "TPC" but expected and seems to be resetting the tire pressures ok.

Also got "PASM Failure". Does this reset itself with some driving?

I probably should consult the manual first.

Turboslut

Extracted from the workshop manual, I thought this might be useful:


Effect of disconnection or total discharge of battery on electrical systems in the vehicle and the precautions to be taken. (MY2005-on)

Control unit memories
Values and faults stored in the control units can be deleted if the battery is disconnected or completely discharged.

• If possible, all fault memories should be checked and, if necessary, printed out before the battery is disconnected.
  
  Supply voltage fault entry
  The entry "supply voltage" may be stored in various control units if the battery has been completely discharged.
• Delete the "supply voltage" entry from the control units in question.
  
  Ready status
  In some countries (presently the U.S.A. and Canada), after disconnecting the battery, it is necessary to reach the Ready status by a test drive and/or by using the Porsche System Tester DME control module menu). If in doubt about this, contact the relevant importer.
  
  DME control module
  With all DME systems, the engine must run for several minutes before the engine control module can relearn the idle speed and mixture adaptation values!
  After disconnection of the power supply, the idle speed might change or fluctuate briefly until the throttle valve adjusting unit has been readapted.
  The mixture adaptation is also lost.
  
  After the battery is connected:
  With the DME, it is necessary to carry out a learning and adaptation routine as described below:
• Switch ignition on for 30 seconds without starting the engine.
• Do not actuate accelerator pedal.
  This completes the adaptation of the throttle valve adjusting unit.
  
  Tyre pressure monitoring system
  When the battery is disconnected and connected, the tyre pressure is first displayed as "- - - ".
• Once the battery has been disconnected and work is complete, the vehicle must be driven for a short distance.
  The actual pressures will then be displayed again.
  
  Steering angle sensor (PSM)
  The steering angle sensor must be re-initialised when the battery is disconnected and connected.
• Turn wheels to straight-ahead position.
• Switch ignition off and then on again twice.
• Start engine.
• From the straight-ahead position, turn steering wheel approx. 20° to the right, past the straight-ahead position.
• Drive the vehicle straight ahead for at least one second at a speed above 4 km/h (2.5 mph).
  The steering angle sensor segment is recognised again in this process.
  Once the sensor has been successfully initialised, the fault code that is stored in the fault memory is documented using the fault deletion counter.
  The fault memory erases itself automatically.
  The PSM indicator light in the instrument cluster goes out.
  
  Power windows
  The end positions of the power windows are deleted from the control unit when the battery is disconnected and connected.
  Perform the following procedure for all power windows:
• Actuate rocker switch and fully close window once.
• Actuate rocker switch once more to close.
  The upper end position of the window is stored.
• Actuate rocker switch and fully open window once.
• Actuate rocker switch once more to open.
  The lower end position of the window is stored.
  
  Instrument cluster
  Clock
  The time is deleted when the power supply is disconnected.
• Press clock control button approx. 1 second on instrument cluster. Hour display flashes.
• Press clock control button in the corresponding direction. Hours can be adjusted.
• Press the clock control button again, the minute display flashes and can be adjusted by turning the clock control button.
  Trip odometer
• The trip counter is set to 0 when the power supply is disconnected.
  
  Airbag control module
  If the battery is disconnected for less than 100 seconds when the ignition is switched on, a CAN time fault, which makes diagnosis of the airbag control unit impossible, may be stored in the airbag control unit.
• The fault is erased by removing the ignition key.
  
  On-board computer
  Disconnection of the vehicle battery deletes the memories for average speed and average consumption. As a result, the displayed range on remaining fuel can be markedly different or even 0. The outside temperature display loses its memory effect. In other words, the indicated outside temperature can be too high due to the heat radiated when the vehicle is hot.
  
  PCM
  When the power supply is disconnected, the built-in GPS receiver loses the so-called almanac containing the satellite orbital paths.
• Switch on PCM when there is a free panoramic view (load GPS almanac); the almanac is reloaded as soon as four satellites have been identifed.
  The date and time are deleted when the battery is disconnected. The summer-/wintertime recognition feature is maintained. The time is lost and is updated again when there is a plausible GPS reception (four satellites).
• The date and time are also adopted once the GPS almanac has been loaded; it may be necessary to change over to summer time (daylight-saving time). This time is transferred to the instrument cluster. If the time is then manually changed by means of the instrument cluster, this time is adopted by the PCM and synchronised with GPS time.
  If the telephone card had been inserted and the telephone was ready for operation, the telephone is subsequently disabled (only if "Use last PIN" is deactivated).
• The telephone is enabled again when the telephone PIN code is entered with the SIM telephone card inserted.
  
  Test drive after disconnecting battery
  Depending on the vehicle equipment fitted, all these work steps are carried out during the test drive.
  Read out the fault memories of all control units after the test drive.
• If there is a fault present, check to see if the fault was caused by an undervoltage.
• If faults were caused by an undervoltage (or CAN timeout error), erase the fault memory, perform another test drive and read out the fault memory.
• If faults were not caused by an undervoltage, correct the faults in accordance with GFF (Guided Fault Finding).