PCM Lost GPS

pmwanderer · May 28, 2010

Hi - first ever post,

I'm a newbie Porsche owner 5 weeks in - awful experience to date...heater packed in, abs and psm failure, battery light on every other day...and my 996 mint only 19k miles from OPC but never mind am bearing with it...

...new problem this week...my PCM doesn't seem to know where I am, the map display shows I am a few hundred yards away from my actual location...what the heck would cause this, can I reset, do I really have to pay another trip to OPC?

Any tips appreciated...

Paul

Richard_Hamilton · May 28, 2010

Paul!!

Could the power have been disconnected? If so, it might be just a case of waiting 20 minutes with the car out in the open. (see bottom of page). If the battery light has been coming on, it is a possibility.

Another thing you could try is a re-boot, by pressing keys 1-4-8 at the same time. (It might be 1-4-7, perhaps someone else could confirm.

These are the instructions for recalibrating the PCM.

HTH

91 12 15 Adjusting (calibrating) PCM navigation unit

General
The PCM navigation unit must be calibrated after maintenance work or commissioning. Calibration is the prerequisite for exact route guidance.

The following components of the PCM navigation unit must be calibrated or initialised:
"” GPS receiver: After an interruption in the power supply (terminal 30), the installed GPS receiver loses its so-called almanac. The almanac stores the satellite orbits and ensures fast location of the individual satellites when the system is started.
"” Distance sensor: The distance sensor transmits the distance travelled to the PCM navigation unit. The distance signal changes if the circumference of the tyre changes (e.g. tyre change). This modification must be calibrated by the PCM navigation unit afterwards.

Note
The distance sensor must be calibrated after commissioning of the PCM navigation unit or after changing a tyre. If a system that has already been calibrated is disconnected from the power supply (terminal 30), the calibration of the distance sensor is retained.

"” Gyroscope: The gyroscope detects changes in the direction of travel and must be calibrated after commissioning.

The gyroscope shows temperature-dependency. This temperature-dependency is compensated by the system if the "cold" (not calibrated) system is switched on and left to stand for approx. one hour.

Note
The gyroscope must be calibrated after commissioning only. If a system that has already been calibrated is disconnected from the power supply (terminal 30), the calibration of the gyroscope is retained.

Procedure after commissioning:

Please observe the sequence!
"” Switch on the PCM with a free panoramic view for approx. 20 minutes (to load GPS almanac).
"” Drive on a motorway if possible at a speed greater than 60 km/h for a distance of approx. 50 km (calibration of the distance measurement).
"” Drive approx. 10 km in an urban area and take frequent turn-offs. Stop for approx. 10 seconds occasionally (calibration of the gyroscope).
"” Switch on the PCM navigation unit for approx. one hour with the vehicle horizontal (temperature compensation of the gyroscope).

Calibration is necessary after the following maintenance work:
"” After changing a tyre
"” After the power supply has been interrupted

Procedure after changing a tyre
"” Drive on a motorway if possible at a speed greater than 60 km/h for a distance of approx. 50 km. (Calibration of the distance measurement).

Procedure after the power supply has been interrupted:
"” Switch on the PCM with a free panoramic view for approx. 20 minutes (to load GPS almanac).

pmwanderer · May 28, 2010

Many thanks Richard,

The power has been disconnected following its weekly visit to the workshop since the dash lit up like Blackpool the other morning.

I did a 1hr commute to today and had the PCM on all the time but mostly motorway so will give it another whirl at the weekend and try a re-set also.

Appreciate the advice - Thanks!

Paul